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By L. M. Wang

Chengmenshan Copper Mine Concentrator adopts the new process of preferential?bulk stage floatation and utilize reground, largely increase the mineral processing index of the copper and the sulphide concentrates. In addition, the paper describes the remarkable economic benefit of the new process through the comparison of the new and the old processes.

Jan 1, 2014

As the high-grade copper deposits in the world become depleted, there is an increasing focus on developing lower-grade ores which contain problematic impurities such as arsenic. Indeed, many high-arsenic ore bodies remain undeveloped because of their high arsenic levels. Separation of arsenic from copper at the beneficiation stage is difficult using the current processing techniques and invariably copper concentrates produced from these ores contain high arsenic levels, sometimes so high as to make them unacceptable to copper smelters. New, sustainable approaches are needed to allow development of high-arsenic copper ores while at the same time minimizing arsenic dispersion into the biosphere. The most promising route for separating arsenic from copper at the flotation stage centers on the use of pulp potential control. In recent years CSIRO has demonstrated at laboratory scale, for a number of high-arsenic copper ores, that crude flotation separation between arsenic-bearing minerals and copper-bearing minerals can be made. The differences in specific minerals responses to changes in pulp potential and pulp pH are exploited for this separation. Such separations nominally produce a low-arsenic high-copper concentrate and a low-copper high-arsenic concentrate. The former can be smelted without penalty, while the latter requires further treatment to capture and stabilize the arsenic and to recover the residual copper. Consideration has now been given to treatment options for the high-arsenic low-copper product. A pyrometallurgical option, involving a low temperature roast to selectively fume off the arsenic and leave a high-copper calcine, coupled with an arsenic stabilization step, has been demonstrated in the laboratory, and a preliminary techno-economic evaluation shows the process to be economically favorable. These results were recently published. CSIRO has now investigated an alternate hydrometallurgical option, involving atmospheric alkaline sulphide leaching of the high-arsenic product, where the arsenic is selectively dissolved leaving a copper-rich leach residue. The leaching testwork was carried at on the same high-arsenic low-copper material used in the roasting studies, enabling a techno-economic comparison of the alternate roasting and leaching treatment options to be made. The alkaline leaching work is briefly described and the results of the process option comparison presented and discussed. Keywords: arsenic, copper, economics, enargite, ore flotation, tennantite INTRODUCTION

Sep 1, 2012

By Aline Tavares

This paper describes the investigative studies carried out at Vale´s Center of Mineral Development (CDM) for a nickel sulfide deposit aiming to develop an adequate flotation flowsheet. The CDM facilities comprises of very well equipped laboratories to develop hydrometallurgical, comminution, flotation, physical separation processes, besides chemical and mineralogical laboratories, that are required to accomplish pre-feasibility studies, new process routes developments and, eventually, brownfield projects. Close association of the flotation group with the geometallurgy and the mineralogy teams play a key role during greenfield project development. Most of the information required by process engineers responsible for the flowsheet development can be provided by the mineralogy team and its mineralogical laboratory at CDM. During the flowsheet development of this nickel sulfide deposit, two ore types were identified as the most abundant in the deposit, named biotite-chlorite hydrothermalite (HID) and magnetite hydrothermalite (MAG HID). Six samples were selected for the investigative studies based on this initial information. Nickel grade varied from 0.39% to 1.95%. The main nickel-bearing minerals were millerite and pentlandite whereas the main non-sulphide gangue minerals were quartz, plagioclase, biotite, chlorite, actinolite, and/or magnetite. Electron microprobe (EMP) identified the presence of nickel in solid solution in gangue minerals such as biotite, chlorite, and actinolite. Nickel deportment in silicates varied from 3% to almost 40%. Magnesium was distributed in biotite and chlorite, except in sample MAG HID, in which talc was responsible for almost 50% of the Mg content. Liberation studies indicated that the optimum feed grind size was around 150µm and that pyrite occurred highly associated to the nickel sulfides. The flotation tests were planned based on the information provided by the mineralogical data. Rougher flotation tests indicated that the optimum P80 of the primary grind was 212µm for the HID type and 150µm for the MAG HID. From the reagents tested, amyl xanthate proved to be the most efficient in the recovery of the sulfides. In the MAG HID sample talc was well depressed by dosing 600g/t of CMC. Nickel recoveries in the rougher stage were lower than 90% due to the nickel distributed in silicates. However, sulfur recovery was around 95%, indicating high recovery of the total sulfides. Open circuit and locked cycle tests were conducted to evaluate the effect of the regrind size in the nickel grade and recovery (P80 of 44µm and 20µm). Nickel recovery decreased from 70% to 65% when finer regrind size was tested. Although nickel recovery decreased by 5%, the finer regrind size lead to a higher Ni grade (from 11% to 23%Ni) and lower fluorine grade (from 1138ppm to 700ppm) in the concentrate. Keywords: nickel sulfide, flotation, mineralogical characterization, flowsheet development

Sep 1, 2012

By Behzad Vaziri Hassas, Firat Karakas, Mehmet Celik, Onur Guven

Since dewatering is a costly process, removal of moisture from relatively fine size lignites is an important industrial problem. As the lignite gets finer, the presence of micropores and relatively low hydrophobic nature of lignite lead to trapping of large quantities of water in the coal matrix. Lignites used in power stations need to be dried to a certain degree of humidity before it is transferred to the combustion chamber. It is generally wise to dewater coal as much as possible by physical means before it is dried. However, dewatering cost in some cases may be prohibitive. Thus, sometimes removal of even little percent moisture may be of great help in such operations. Surfactants have been used to increase the efficiency of coal dewatering. It is crucial to select appropriate type and amount of surfactants in order to get higher efficiency. Since the hydrophobic characteristic of coals increases with increasing the coal rank, dewatering of bituminous and anthracite can be accomplished using low HLB surfactants (Oily), however, these surfactants are not efficient in the case of low rank coals like lignites and brown coals. It is suggested that adsorption of low HLB surfactants on high rank coals is governed by Acid-Base interactions rather than electrostatic and van der Waals forces. Since this characteristic in lignites is not strong enough, low HLB surfactants could not be effectively adsorbed on low rank coals to make surface more hydrophobic. In this paper, a special set-up has been designed to study the effect of high HLB surfactants on dewatering of fine lignite particles. It is shown that high HLB surfactants function more efficiently on low rank coals than low HLB ones.

Jan 1, 2014

By Z. G. Guan

The tungsten ore in Xingluokeng belongs to a symbiotic deposit containing granite and fine vein-type wolframite and scheelite. The tungsten (WO3wolframite) accounts for only 0.233% of the raw ore, 49.60% of the , 49.60% of the scheelite and 0.8% of the tungstite. The dissemination size of the tungsten ore is extremely uneven, with 0.02~1.28 mm for scheelite and 0.01~1.28 mm for wolframite. The dissemination size of scheelite is coarser than that of wolframite. The size of 83% of scheelite and 60% of wolframite is greater than 0.04 mm. The composition of minerals in the ore is quite complex. The major metallic minerals include wolframite, scheelite and pyrite, which are followed by molybdenite, chalcopyrite, arsenopyrite, limonite, magnetite, hematite and siderite. The major gangue minerals include quartz, feldspar, muscovite, biotite and sericite, which are followed by chlorite, fluorite, apatite, dolomite, etc. According to the dissemination features and liberation degree of the tungsten minerals, the technology flowsheet of gravity concentration for coarse particles and flotation for fine particles to re-cover the low-grade and fine vein-type tungsten minerals is adopted, and -0.7 mm is selected as the processing size. The closed-circuit grinding procedure, with the combination of the rod mill and high-frequency vibration screen, is adopted. The grinding product is classified into three products of -0.7 +0.2 mm, -0.2 +0.04 mm and -0.04 mm. The gravity separation is adopted for the former two to recover tungsten minerals and the flotation is adopted for the last one. Under the condition that the raw ore contains 0.23% WO3, some technology indexes of beneficiation have been achieved. The gravity tungsten concentrate contains 63.54% WO3 with the recovery 70.11%. The slime flotation tungsten concentrate contains 35.22% WO3 with the recovery 10.48%. The composite tungsten concentrate contains 57.53% WO3 with the recovery 80.59%. Thus, the tungsten minerals are re-covered effectively.

Jan 1, 2014

By Heiko Schiemann, Christoph Beyer, Thomas Pretz

"Due to multiple experiences in the field of planning and engineering of processing plants for secondary materials the Chair for Processing and Recycling of Solid Waste Materials decided to develop a software tool that supports the engineering and the planning of the basic layout of processing plants for secondary material flows. The detailed description of the material flow and its characteristic parameters is one of the main tasks to be worked out and should be considered as the basis for representative simulation results.The description of the material flow and its characteristic parameters is based on a fraction vector containing 12 material fractions. This is a compromise between a detailed material flow description and a compact and therefore time-extensive calculation model. Each material fraction is characterized by 15 parameters, which can be edited with the help of an easily accessible user-interface. In addition to basic parameters like ignition loss, water content and calorific value more parameters like the material fraction-specific particle-size distribution are contained. Using the model library SimuRec, the processing success and the recovery of complex processing plants for secondary materials can be predicted."

Jan 1, 2003

By J. Qiu

By means of natural sedimentation, two different bentonite samples from Shandong province were purified, this paper studies the Hydro-properties of the two purified montmorillonite samples. Firstly, the layer charge of two purified montmorillonite samples were calculated by crystal structure formula reckon method and general hydro-properties were also measured. The research results showed that the layer charge of montmorillonite correlated well with its hydro-properties: mont-morillonite with lower layer charge had better hydro-properties, such as Mont-1, which had higher swelling volume and gelling value with lower CEC; while, montmorillonite with higher layer charge had worse hydro-properties, such as Mont-2, which had lower swell volume and gelling value with higher CEC; it proves that the hydro-properties of montmorillonite depends on its layer charge characteristics, layer charge characteristic is the inherent factors deciding the hydro-properties of montmorillonite, montmorillonite with lower layer charge has better hydro-properties than the one with higher layer charge. In this paper, the relation between the medium condition and colloid performance of Mont-1 are also studied. The results show that the hydro-properties of Mont-1 could be changed by changing slurry concentration (w/w) and shear rate or adding certain amounts of inorganic cation electrolytes, dispersants and surfactants. The viscosity of montmorillonite slurry could be enhanced by increasing slurry concentration,adding univalentcation electrolytes (less than 4% w/w) or proper amounts of dispersants and surfactants (less than critical micelle concentration); The slurry viscosity could be reduced by decreasing slurry concentration, increasing shear rate, adding proper bivalent (more than 4% w/w) cation electrolytes or proper quantities of dispersants and surfactants (more than critical micelle concentration).

Jan 1, 2014

Nowadays, the more successful plants are those who have adopted effective and efficient strategies to optimise their plant operation. As the ?heart of the plant? could be viewed as the mil-ling/grinding area, one of the key steps in plant optimisation is, therefore, ensuring the mill is operating properly. In the past, when primary, secondary and tertiary crushers fed material directly to large ball mills, the energy efficiency of the concentrator was determined for the most part by the ball mill operation, whereas now the energy efficiency of a plant often rests largely on the semiau-togenous grinding (SAG) mill operation. As a result, mines have shifted their emphasis in optimization from ball mills to SAG mills. The grinding mill?s energy efficiency essentially depends on ore characteristics and the discharge rate of broken particles, which in turn depends on how efficiently the discharge pump (grate and pulp lifters) operates. The essential function of pulp lifter being to transport the broken material and slurry out of the mill, its design optimization therefore affects the discharge capacity (or mill throughput) of AG and SAG grinding mills. This paper will discuss how the optimised design of the pulp lifter/ discharger has helped to eliminate material transport issues such as flow-back and carry-over of slurry and pebbles to in-crease the energy efficiency of SAG mill using the actual operational data.

Jan 1, 2014

By S. Sarioglan

The bleaching of edible oils, industrial oils, and some chemicals may be achieved using natural and acid-activated clays. These materials remove impurities and pigments from the oils. In this work, a bentonite clay from Turkey (Somas bentonite) was activated with different concentration of H2SO4 and HCl at 70~90°C and 5~8 hours. Under these conditions several cations were removed from natural bentonite (Al, Mg, and Fe) and DTA-TGA, FT-IR curves of the solids obtained after acid treatment were examined. Treatment time and acid concentration increased the degree of destruction of the bentonite structure which was determined by ICP. Activated samples were tested in order to verify their capacity to bleach soybean oil and compared to standard commercial bleaching clays. The experimental results indicate that treated samples with H2SO4 have the same efficient in bleaching crude soybean oil with the standards and treated sample with HCl is more efficient in bleaching than the commercial products.

Jan 1, 2014

By Jing Zhou

In view of the state of the long time use of sodium cyanide in lead-zinc-sulfur-silver multimetallic ore production, we propose alternative reagents system through experimental research. The experiment first used TJ, sodium sulfide to adjust the flotation pulp, after that, zinc sulfate, sodium sulfite was added to low alkaline pulp to inhibiting zinc sulfur mineral and adapted MB, 25# aerofloat and diethyl dithiocarbamate combination collectors to float lead minerals. The obtained test index is as follows: lead concentrate recovery rate of small scale test was increased by 5 to 10%, the recovery rates of gold and silver in lead concentrate were increased by 7% and 11% respectively; the industrial test is conducted under the condition that the total grade of lead and zinc content in raw ore decreased by 4.81%, the total recovery rate of lead and zinc increased by 7%, recovery rates of gold and silver in lead concentrate were increased by 7.62% and 9.65% respectively. So it successfully realizes the target to replace the sodium cyanide, using low-alkaline non-toxic reagents system in mineral processing practice of three kinds of complex lead-zinc-sulfur ore of this mine. Keywords: refractory lead-zinc-sulfur ore, depressant, non-cyanide flotation

Sep 1, 2012

By M. Saghaeian, R. Hejazi, M. Farahani, M. Dehghani, A. Tohry

"Wet tailing dams of iron ore processing plants typically contain a significant amount of valuable minerals. In more recent years, due to the increase in iron’s prices and technological innovations, as well as the low energy consumption which required for processing of materials from tailings, dams can consider as potential valuable deposits. However, the production of iron concentrate from tailings is usually complicated where the high moisture content of the material, the high clay content and the presence of chemicals of processing such as flocculants, acids and flotation reagents, all make materials highly sticky which can be easily swollen. In the present paper, the optimization of operational parameters to recover ultrafine hematite iron ore from the wet tailings dams of the Chador-malu iron ore mine was investigated. The optimization of operational parameters, showed that with modification of the washing unit components for slurry making, the challenge of constraints from feeding the plant could be overcome. To decrease the magnetite content in the tail stream of the medium intensity magnetic separation (MIMS) and subsequently increase the efficiency, the orifice of the cleaner tail flow exit pipe was changed from 7 inches to 3 inch and yoke angle changed from 14 to 8 degrees. These changes increased mass yield by 3% and decreased the magnetite content in the final tailings to 1.2%. By recirculating the cleaner SLons of final tailings within the circuit, the solid percentage of the feed to rougher SLons decreased to around 15%, and as a result the matrices were not overloaded that easily, and mass yield increased to about 13% from 7%. All the above mentioned optimizations were achieved without significantly affecting the concentrate Fe grade."

Jan 1, 2018

By Luís Marcelo Tavares, Daniel Francioli, Malcolm Powell, Mohsen Yahyaei

"Mathematical modeling of the comminution process requires understanding of all breakage mechanisms occurring in this mechanical environment. Modeling of high energy impact breakage is well established, however, modeling low energy breakage including incremental damage breakage, attrition and abrasion is still under development. Free fall incremental impact tests were carried out to investigate the surface fragmentation of a copper-gold ore. This process was achieved by dropping particles individually from a height of four meters onto a metallic plate. The impact specific energy was 0.01KWh/t. The setting of the metallic plate was changed to test the impact angles of 0°, 45°, and 60°. Tests were carried out using fresh angular rocks as well as smoothed particles. Changes to the plate angle and particle shape enabled the study of the influence of the tangential component of the impact energy along with particle shape on superficial breakage. By studying the fractional mass loss variation in each impact, two distinct stages of surface fragmentation were clearly determined: high fractional mass loss dominated in the first 10 impacts and was attributed to chipping, whereas low fractional mass loss occurred for the remainder of the impacts and was attributed to abrasion. Smoothed particles demonstrated higher resistantance to breakage and their surface fragmentation behavior indicated a closer relationship to abrasion, especially when lower impact angles were used."

Jan 1, 2014

By G. Alfano

We have investigated the breakage actions of solid particles observed in a new generation fluid energy micronizer being set up at our laboratories. The attention has been focussed in particular on breakage caused by interparticle collision, particle impact against a fixed surface, interparticle attrition and particle against wall of jet mill attrition. We have also studied the influence of grain size distribution, maximum particle size, flow rate and characteristics of the solid to be processed, as well as of flow rate and pressure of injected air on the above mechanism. Lastly, the operating parameters of a dynamic air classifier in closed circuit with the micronizer for recovering the fine fraction and automatically recycling the oversize, have been optimized. The findings of this investigation have been used to design, build and fine tune a micronizer capable of controlling the top size of a product having average particle size that meets market requirements for fine powders, while keeping power consumption relatively low.

Jan 1, 2014

Results of the study of chloride ion concentration effect to osmium-187 sorption from wastewater of copper smelter with use of foreign anionites of different basicity and structure are presented in the work. It was found that the increase of chloride ion concentration in the wastewater helps to increase recovery of osmium using anionites regardless of their nature. The ways to intensify the process are proposed. The method for osmium elution from the anionites with potassium iodate solution was developed. It was shown that the method lets to recover up to 99% of osmium from the anionites. Recommendations for selection of eluents for better recovery of osmium from the anionites were elaborated. Keywords: wastewater, osmium, anionite, sorption, chloride ions, eluent, recovery

Sep 1, 2012

By I. A. Khabarova

The paper presents the results of experimental investigations of the effect by high-power nano-second electromagnetic pulses (HPEMP) on change of surface composition, physical-chemical and flotation properties of pyrrhotite, and search of optimal combination of flotation reactants providing increase of metal extraction from disseminated copper-nickel ores. Preliminary electropulse effect on products before flotation allows to create optimal conditions for flotation separation of pentlandite and pyrrhotite owing to forming the new phases and defects on the surface of sulphides. It was established, that the yield of monomineral fractions of pyrite, pyrrhotite and chalkopyrite increases by 5%~15 %, compared with flotation with one butyl xanthenes (BX), during usage of combination of thionic carbamate (isopropylmethylthionocarbamate (ITC) or isopropylethyl- thionocarbamate (Z-200) with butyl xanthate (BX). Sorption of investigated reactants and strength of their fixing on the surface of minerals are examined; it helped to reveal the cause of rise of floatability of sulphide minerals for the case of combination of reactants. Preliminary high-pulse processing and reactant conditions with usage of combination of thionic carbamate and xanthate have been tested on the sample of disseminated copper-nickel ore from Norilsk region.

Jan 1, 2014

By A. O. Gapchich, T. N. Matveeva, N. K. Gromova

"Tin sulfide ores and aged man-made products obtained after their processing are distinguished by a complex material composition and uneven impregnation of sulfide minerals (chalcopyrite, galena, arsenopyrite, etc.) and tin ore (cassiterite). Enrichment of such ores is performed through sophisticated multistage schemes using not only gravitational methods, but also gravity flotation, flotation, magnetic separation techniques. Tin ores also contain rare and precious metals (indium, scandium, silver), characterized by fine dispersity and microscale to nanoscale fineness of mineral formations. During flotation concentration these metals are extracted along with the main ore minerals into concentrates (tin, copper, tungsten, etc.), however, up to 10-20 % of them are lost with final tailings. The aim of the work is an experimental study of the modification of the surface of sulfide minerals and cassiterite by stable metal-collector complexes to increase extraction of fine tin, silver, copper and other metals from complex tin ores. Triamide cyanuric acid (TCA) was studied as a thin silver flotation modifier. Thermophilic polymer with a functional group of phenylphosphine TMPPh was used as a selective flocculant. For experimental studies of the physical and chemical effects of collecting agents on the surface of minerals the following analytical techniques were used - the analytical scanning electron emission ASEM (LEO 1420VP INCA OXFORD ENERGY 350) and laser (KEYENCE VK-9700) microscopy, measurements of electrode potentials of mineral anthills by potentiometric titration, monomineral and pulp flotation. New data on formation of the adsorbed layer of DBDTC on the surface of chalcopyrite, galena and arsenopyrite were obtained, and the dimensions of the reagent films and the strength of their adsorption. The indiscriminateness of cassiterite to DBDTC ensures its selective separation into a chamber product during the flotation of sulfides. It is shown, that modification of the sulfide surface by stable complexes Me-DBDTC and Ag-TCA-TMPPh will increase the recovery of non-ferrous metals and silver into a collective sulfide concentrate and will provide a high-quality tin concentrate for flotation of tin sulfide ores.The studies were perfomed with the aid of the Russian Science Foundation (Project No. 17-17-01292).INTRODUCTIONTin sulfide ores and aged man-made products obtained after their processing are distinguished by a complex material composition and uneven impregnation of sulfide minerals (chalcopyrite, galena, arsenopyrite, etc.) and tin ore (cassiterite). Enrichment of such ores is performed through sophisticated multistage schemes using not only gravitational methods, but also gravity flotation, flotation, magnetic separation techniques. Tin ores also contain rare and precious metals (indium, scandium, silver), characterized by fine dispersity and microscale to nanoscale fineness of mineral formations. During flotation concentration these metals are extracted along with the main ore minerals into concentrates (tin, copper, tungsten, etc.), however, up to 10-20 % of them are lost with final tailings. In this regard, it seems advisable to use new varieties of flotation reagents in order to increase extraction of finely dispersed tin, silver, copper and other non-ferrous and precious metals from multi-metal tin ores (Bocharov and Ignatkina, 2007; Khanchuk etal., 2012; Wu and Zhu, 2006; Yusupov etal., 2016)."

Jan 1, 2018

By Susanna A. C. Stadler, Chris Aldrich, Jacques J. Eksteen

Slag foaming occurs in several pyrometallurgical processes. These processes include steelmaking in basic oxygen steelmaking furnaces and electric arc furnaces as well as various non-ferrous operations like sulphide smelting/converting and base metal slag cleaning. Although slag foaming in steelmaking processes has been extensively researched, little attention has been given to slag foaming in non-ferrous operations. Slag foaming phenomena are complex because often the system consists of three or more phases. With this in mind, factors previously identified as influencing slag foaming were investigated. These include the slag basicity, physical properties of the slag, namely viscosity, surface tension and density, the formation of particles due to undercooling of the slag and the FexO concentration in the slag. The effect of increasing FexO concentration was found to decrease the foam index due to lower viscosities, but higher surface tension depression appears to have led to increased foam index values at high FexO concentrations. The foaming index decreases with increasing basicity, until precipitation of solids occurs. After this point, the foaming index was found to increase with increasing basicity due to increased solids precipitation. In general, increasing amounts of slag-wettable solids led to higher foam indices, but the precise nature of the effect on slag foaming was dependant on the nature of the solid precipitate.

Jan 1, 2003

By U. A. Peuker

"Steam Pressure Filtration (SPF) is a modified cake filtration process and is characterized by both washing and excellent de-watering of the filter cake. Compared to conventional gas differential pressure filtration, the filter cake is treated with saturated or superheated steam replacing pressurized air. Invented in the early last century, Steam Pressure Filtration has reached technical maturity in the 1990ies for inorganic particle systems, fine chemicals and coal. Especially the de-watering performance for fine particles systems below 50 µm make Steam Pressure Filtration an excellent option for the processing of fine tailings streams, to produce a stable material, which can be described by the methods of solids mechanics instead of paste rheology. The washing, which is due to the condensing steam, is able to reduce the ion load of the solid. This additional effect is able to generate a dry tailings material, which shows a reduced leaching potential of mobile ions, which originally derive from the process water. INTRODUCTION Steam Pressure Filtration is a process concept especially of hyperbaric filtration, which started its market entry in the 1990ies (Bott 1996, Bott 2002). Even though there have been many attempts to apply steam on filters before, the success story began with the combination of hyperbaric filtration and steam application and the technical solution to limit the steam treatment to a defined zone on the filter. This resulted from the scientific findings that steam mainly enhances the de-watering during the mechanical filtration (Gerl 1999). There are no or minor positive effects of steam application to a filtration process during cake filtration and after the steam breakthrough has occurred. Furthermore that time a sufficient control technology to regulate the steam consumption as well as suitable filter cloths became available. There is a growing need for de-watering technology in the mining industry, not only for the concentrate but also for the tailings streams. Several reasons argue against the established solution of damping the tails as suspension or paste into tailings ponds. There are ecological, political, societal and economic reasons, which question the tailings ponds more and more. Due to the increasing costs in the building and monitoring of tailings dams, which contain the tailing ponds, the concept of dry stocking using filtration technology comes into the game (Jansson 2016). Dry stocking converts the tailings stream form the suspension or paste state, into a material, which can be stockpiled. The latter typically is a moist flowable disperse particle system. The conversion involves a de-watering step, in which different types of filter equipment can be used, e.g. filter presses, membrane filter presses, automatic press filters or hyperbaric filters. For coarse products also vacuum filter can be applied. Due to its excellent de-watering performance and the easy scale-up properties Steam Pressure Filtration is further option for dry tailings stacking."

Jan 1, 2018

By G. Bulut, Ü. Yenial

"Heavy metals contamination in aqueous systems can be found in a variety of industries, in particularly mining, metal processing, finishing and plating. Water containing more than 0.5 ppm heavy metal considered as a toxic due to harmful effects on health. The major techniques employed for heavy metal removal from industrial wastewaters include precipitation, reduction, ion-exchange, and adsorption. Adsorption is a heavy metal removal method for aqueous systems. As a common adsorbent, activated carbon has been used in treatment but it is ineffective on some elements. Thus, there has been a research for developing highly effective and selective adsorbents. In this study the adsorption of lead and arsenic ions on to coal waste and red mud waste was studied. The experimental parameters were determined as pH, equilibrium time and the initial concentrations, activation by heat treatment and the blend of adsorbents. According to their adsorption capabilities, red mud was found to adsorb lead and arsenic ion with high efficiency but coal waste did not adsorb arsenic ion. However the binary adsorptions of these ions were enhanced the adsorption efficiencies. In addition the blend of coal waste and red mud affected the adsorption efficiency. INTRODUCTION As a result of rapidly developing industry and excessive use of water resources, the need of clean water and wastewater management appear as a problem. Wastewater recycling activities and researches come to the fore for an effective use of wastewater. Recycling of wastewater, which contains heavy metals harmful to the environment and human, is a difficult process. Heavy metals are generally divided into three categories: toxic metals, precious metals, radionuclides. Wastewaters from various industries, containing heavy metals, are the main polluters of water and soil. Although their toxic structures, heavy metals are used extensively in industry as they have technological significance. Usually mining industry, metal industry and industrial organizations produce heavy metal containing wastewaters (Volesky 1990, Ting and Lawson 1991, Bishop 2002)."

Jan 1, 2018

By Carina Ulsen

The existing construction and demolition (C and D) waste recycling technologies and standards have been essentially focused on the production and use of coarse recycled aggregates. Very few papers focus on the production of recycled sand, although some previous results show that fine aggregates fraction represents around 40 to 60% (in mass) of the Brazilian waste and it is usually used as road sub-base or disposed in landfills. The quality of the recycled aggregate is strictly related to the content of porous and low strength phases, mainly the patches of cement remaining on recycled aggregate surface. Some technologies have already been described in the literature, even though, to the moment none of these technologies has clearly succeeded in reaching the large market available. This paper presents a summary of the main properties of the sand produced from C and D waste by tertiary crushing at vertical shaft impact crusher (VSI). Additionally mineral processing technologies were applied on the attained product, such as gravity concentration by shaking table and spirals and removal of cement paste by attrition. The main properties of recycled sand are discussed and compared to the previous C and D waste, respectively: particle size distribution, particle shape, chemical composition, cement paste content and porosity. The results demonstrates that the crushing allowed producing a VSI-sand with low porosity and water absorption due to the increasing on the content of silicates from natural rock phases and increasing liberation between these phases and porous cement paste; the particles from the attained product presented also a better shape (sphericity and aspect ratio). The attrition tests assayed on VSI recycled fine aggregates accomplished a further selective disaggregation of cement paste and other porous materials - the porosity was reduced from 10% to 7%. The concentration by shaking table at narrow sieve fractions led to a product with low porosity and reduced content of cement paste, however, concentration on spirals did not succeed since separation was performed essentially by the size of the particles. The heavy product from shaking table represented almost 75% in weight and has less than 60% recovery of CaO+LOI, and expressive reduction on porosity. The aim of producing sand from construction and demolition waste through mineral processing unit operations changes the recycling approach and contributes for up cycling the recycled sand. The exhaustion of sand deposits on Brazilian large centers, the increasing price and the construction boom encourages the development of alternative materials as construction raw material. Keywords: recycled sand, construction and demolition waste, technological characterization

Sep 1, 2012