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By Y. Q. He

The dynamic behaviors of the air bubbles in the dense gas-solid fluidized bed have a significant effect on the performance of dry coal separation. The combined method of experimental measurement and numerical simulation were conducted to conduct the research of the mean diameters and rising velocities of the bubbles in the fluidized bed. The calculation models of mean diameter and rising velocity of the single bubble were proposed. The results indicate that the models of the mean diameter raised by Rowe (1976) and the rising velocity raised in this work could be used to predict the bubble dynamic parameters in gas-solid fluidized bed. With the Geldart B type of magnetite powder as the medium solids and while the gas velocity of 1.5Umf=U=2.2Umf, the mean bubble diameter along the bed height is 36mm<Db<45mm, and the mean rising velocity of the single bubble is distributed in 40~65cm/s. The results of experimental measurement, numerical simulation and model predication provide well agreements finally. Based on the uniform fluctuations of air bubbles diameters and their rising velocities, the separation experiments of 50~6mm dry coal using the mixture of 0.3~0.15mm magnetite powder and <1mm fine coal as medium solids were carried out. The results show that the probable error, E is 0.06, which indicates a good separation performance by using the gas-solid fluidized bed. Keywords: dense gas-solid fluidized bed, bubble dynamic behaviors, numerical simulation, separation performance

Sep 1, 2012

By U. M. J. Boin, W. L. Dalmijn, T. P. R. de Jong

"This paper explores the complex interrelationship between the resource cycle, recycling and metal production as a function of economics, environmental legislation, and product design. It is argued that central to optimising this resource cycle lies the control in particular of physical separation plants by the application of advanced sensor technology and sorting equipment, as well as suitable control and sampling algorithms supported by optimising mass balance models.Metals are produced through a long chain of processes. For primary resources, metals production goes through mining, mineral processing, ore smelting, conversion and refining steps or via low temperature hydrometallurgical processes, or a combination of both pyro- and hydrometallurgical operations. For the recycling of resources, metals are separated and recovered from metal scrap, which plays an increasingly important role in the world. Metals after being produced, either from primary or recycling resources, have to be further refined or manufactured into various types of alloys and finally shaped into different products for the end-users. Since the end-user discards products the contained materials find their way back into the resource cycle as scrap. Therefore, controlling the metallurgical reactors also controls, in a much broader sense, the material quality in the complete metals cycle, from the production phase, to the end-use phase, up to the recycling phase (Reuter et al., 2003). The recycling phase includes separation of materials into saleable intermediate products, which are reintroduced into the production phase as a recycling resource. Therefore, the metallurgical processes in each unit operation in the metals production and processing chain have to be controlled, so as to achieve optimal performance of high product quality, low energy and materials consumption, and low environmental impact."

Jan 1, 2003

By S. Q. Zhu

Coal Water Mixtures (CWMs) are densed suspensions of coal particles in water. Viscosity is one of the most important rheological properties of CWMs and it is desired to be as low as possible. The slurry viscosity was influenced significantly by additive formation, the particle size distribution and the ash content of the coal. However, the influence of dispersants is most obvious. At present, there are several kinds of dispersants such as polymeric styrene sulfuric sodium, lignin sulfonate, humate, polycarboxy salt, ethylene epoxide surfactant. In this paper, a newly synthesized CWM dispersant has been reported, which is an efficient anionic surfactants of polycarboxylic acid type. The synthesis process includes three steps. At the beginning, the polyglycol acetate ester has been performed by acetic acid and polyethylene glycol (PEO) on the condition of acetic-acid/PEO ratio 1:1.1, at 368~373K for 30 minutes. Then the macro-monomer is prepared through the esterification of 85.71% acrylic and 14.29% polyglycol acetate ester, at 368~373K for 10 minutes. After that, the polycarboxylic acid CWM dispersant is polymerized using proper proportion macro-monomer, acrylic (AA) and sulfonic styrol sodium, at 368~373K for 1 hour. This new dispersants are used in the coal water mixtures formulation. Four kinds of coal used in the experiment are Shuang Yashan, Tunliu, Luning, Changcun samples. ? The highest concentration for shuanyashan coal is 70% when the dosage of dispersant is 0.4%, and the content of -200 meshes particles is 75.53%. As the dosage of dispersant de-creases to 0.25%, the Shangyashan CWM concentration is 67%. ? For Tunliu coal CWM concentrations are in the range of 76% to 75% when dosage of the dispersant changes from 0.4% to 0.25% at the same particle size distribution of 83.5% minus 200 meshes. ? The highest concentration for Luning coal is 69% when dosage of the dispersant is 0.4%, and the content of -200 meshes particles is 88.86%. ? For Changcun sample, the coal concentration of CWM is 73%~75% when dosage range of the dispersant is 0.35%~0.5%. The experiments show that the synthesied dispersant is quite promising for some coals CWM preparation, but a little bit coal-dependent. The Proximate and Ultimate analysis, surface characteristic measurement have been made to investigate the interactions between coal and additives.

Jan 1, 2014

Considerable attention has been, and is being, given to the physics of water-films associated with bubble interactions at surfaces. In contrast, little information on the chemistry of such films has been reported. This communication reports a method using sum frequency vibrational spectroscopy (SFVS) to describe hydrogen bonding of interfacial water molecules in water films created with bubbles at hydrophilic and hydrophobic surfaces. The SFVS spectra of water films at hydrophilic silica surfaces differ significantly from the spectra of water at a hydrophobic silica surface. The SFVS spectra indicate that a very ordered water structure exists in water films at the hydrophilic silica surface during contact with a bubble and that the extent of hydrogen bonding increases with an increase in contact pressure. Such structural considerations as well as repulsive electrostatic and Van der Waals forces account for film stability for a bubble at the hydrophilic silica surface. In contrast, the SFVS spectra of water at a hydrophobic silica surface show a lack of hydrogen bonding and are characterized by a distinct absorption at about 3700 cm-1 similar to the spectrum of the air/water interface. These results suggest the presence of a water void, or water exclusion zone, at the hydrophobic surface, as supported by X-ray reflectivity measurements reported in the literature, by atomic force microscopy, and by the results from molecular dynamics simulations. Of course the water film at the hydrophobic surface is unstable with film thinning and rupture upon bubble contact. Under these circumstances it is shown that an attractive Van der Waals force between the bubble and the hydrophobic surface can be expected when the water exclusion zone is taken into consideration. As the thickness of the water exclusion zone increases to a thickness corresponding to the size of nano bubbles, the calculated attractive Van der Waals force increases. This analysis may help to explain the so-called ?short range? and ?long range? hydrophobic forces. Keywords: SFVS spectra, hydrophilic silica surface, hydrophobic silica surface

Sep 1, 2012

By A. Akcil, O. Celep, C. Erust, E. Y. Yazici1, H. Deveci1

"Recycling of WEEE has already gain prime importance from both environmental and economic point of view. For the recovery of metals from e-waste, many conventional physical, bio/hydrometallurgical and pyrometallurgical processes are proposed. Economic potential of e-waste is mainly driven by its precious metal content. Physical separation methods (e.g. electrostatic, magnetic, eddy current and gravity separation) exploit the differences in the physical properties of metals and non-metals. Physical separation methods are simple and economically sound but they suffer from metal losses and ineffectiveness at fine sizes. Hydrometallurgical processes are promising owing to their relatively low cost, reduced environmental impact, potential for high metal recoveries and suitability for small scale applications. Hydrometallurgical processes can be developed for selective extraction of base/precious metals using suitable reagent systems. Sulphate-based leaching with a suitable oxidant (e.g. H2O2, O2, Fe3+) is effective for copper and other base metals. After removal/recovery of base metals, precious metals can be easily extracted using various lixiviants including thiosulphate, thiourea, cyanide and chloride. However, further research is required to develop new, cost effective and environmentally friendly processes and/or refine existing ones for leaching and, in particular, downstream processes. INTRODUCTION Electrical and electronic equipments are indispensable to modern societies with numerous applications in the field of medicine, transport, communication, education, security and environmental protection. With technological developments and innovations, the replacement of old equipment leads to ever fast accumulation of waste materials such as waste electrical and electronic equipment (WEEE or e-waste). People are upgrading their mobile phones, computers, televisions, audio equipment and printers more frequently than ever before (Babu et al., 2007; Lee et al., 2007). With the rapid growth in technology today, the life span and utilisation period of most electronic and electrical equipment has been reduced considerably with concomitant generation of huge amounts of WEEE over the past several decades. According to statistics presented by Balde et al. (2015), total WEEE produced around the world was 41.8 million tonnes in 2014 and expected to rise to approximately 50 million tonnes by 2018. Kumar et al. (2017) estimated that annual growth rate for the WEEE stream is 3–5% (Singh et al., 2016). The aim of this paper is to provide an overview of physical separation and hydrometallurgical methods available for the treatment of WEEE."

Jan 1, 2018

By L. M. Sun

Baotou Baiyunerbo Mines Location in Inner Mongolia is a famous deposit of iron mineral and rare earth mineral accreting. The iron ore has very complicated ingredients and minerals composing. In the mine, there is not only magnetite ore but also hematite ore, so that it is impossible for high grade iron concentrate to adopt single wet low-intensity magnetic separation or high-intensity magnetic separation to concentrate iron mineral. Because of mixing the magnetite with hematite mineral in feed ore, recovery of iron of magnetite production system in the mineral processing plant is less than other mineral processing plants. Therefore, the research for increasing recovery of iron of the magnetite production system in the plant was undertaken. The paper presented the research for using dry magnetic separation to increase recovery of iron concentrate of the magnetite production system in the plant. It mainly includes dry magnetic separation test and wet magnetic separation and reverse flotation test. The test results indicated that dry magnetic separation is a important way to improve the feature of feed ore of the magnetite production system and to increase the recovery of iron. The recovery of iron may increase from about 70% to over 80%. The research also presented optimum operation parameters of the dry magnetic separator and the separation flowsheet. In conclusion, using dry magnetic separation to treat with feed ore of the magnetite production system in the plant to increase the recovery of iron is a feasible technique. The research present a new way for the mineral processing plant to made technology innovate to increase the recovery of iron concentrate of the plant in future.

Jan 1, 2014

By Sumantra Bhattacharya

The per capita energy consumption in India is 510kgoe/year, the global average being nearly 1818kgoe/year. Correspondingly low is the per capita CO2 emission at 1.25t against the world average of 4.39t.65-70%, at times more, of India?s power generation from about 190,000 MW installed capacity, is however coal fired.India therefore has to secure diversified sources of energy and solar power is increasingly being looked as the real alternative to the existing over dependence on coal. To ensure sustainable solar power it is essential to secure its raw material base that is ?silica?, hitherto considered as ?minor minerals?. That calls for immediately addressing the issues of land availability, solar power cost, developing a dynamic inventory of silica containing minerals, appropriate processing technology and strong regulatory framework for sustainable mining and processing of all silica rich minerals. Keywords: silica, silicon, Thar, power generation, India, quartz, solar power

Sep 1, 2012

By A. V. Kozub, D. O. Sharkovsky, R. I. Ismagilov

"Due to complex mineral composition and fine ingrained nature concentration of iron ores deposited in Mikhailovskoye mine field requires application of wet magnetic separation to produce 65–66% Fetotal and 8.2–8.6 %SiO2, concentrate with 90–94% of material being –0.044micron grain size. Higher specific consumption of ROM, increase of production costs with concurrent reduction of output - those are inevitable side effects of desired concentrate grade improvement. Large-scale complex analysis and surveys have been carried out aimed at concentrate grade improvement with concurrent output increase. Classification of feed in hydraulic cyclones (hereinafter referred to as hydrocyclones) has been the bottleneck for improvement of processing throughput and concentrate output. Hydrocyclone classification efficiency is 50-60% and further improvement is practically impossible. Actual circulating load may achieve as much as 500-600% while the optimal rate is 200-250%. Application of wet fine screening has been considered to improve iron ore concentrate grade. Objective of this work is to design processing flow diagram for unoxidized ferruginous quartzites with implementation of wet fine screening. Large-scale tests have been run in Crushing and Concentrating Plant with application of wet fine screening stage. These tests included application of wet fine screening in 2 and 3 stages of classification to separate desired grain sized material; replacement of hydrocyclone classification with fine screening; application of fine screening as additional stages to concentration process and screening of final concentrate. Testing Methods. EXPERIMENTS AS WELL AS THEORETICAL RESEARCH HAVE BEEN APPLIED FOR THE PURPOSES OF THIS WORK; INCLUDING MAGNETIC, GRAIN-SIZE AND CHEMICAL ANALYSIS OF CONCENTRATION PRODUCTS. MODERN ANALYTICAL DATABASE HAS BEEN APPLIED TO STUDY WET FINE SCREENING FEATURES, MINERAL AND PHYSICAL COMPOSITION OF CONCENTRATION PRODUCTS. Work Results: - analysis of wet fine screening application for iron ore concentration. - technological solutions enabling to improve slurry classification of fine ingrained low magnetic iron ore have been developed. - effective process flow diagram including fine screening has been designed based on the feasible and reasonable arrangement solutions."

Jan 1, 2018

By Fengnian Shi

In the current energy-sensitive world, sustainable development in the mineral industry will require new, better and more efficient processes. Novel comminution methods, which offer the prospect of achieving the required outcomes of size reduction and mineral liberation at lower energy consumption, are continually being sought. In the past five years, extensive research using high voltage pulse electrical comminution technology has been carried out at the Julius Kruttschnitt Mineral Research Centre (JKMRC), in collaboration with selFrag AG. The major outcome of this research is the development of the concept of pre-weakening ore particles by electrical comminution procedures to reduce the energy consumption in the downstream grinding circuit. The research has also verified the preferential liberation of valuable minerals by electrical comminution. Given the advantages, several potential applications of electrical comminution in the mineral industry are proposed, including AG/SAG mill feed pre-weakening, pebble treatment, ball mill feed pre-weakening, early recovery of the liberated valuable minerals, crack/micro crack generation for improved leaching, and smelter slag treatment. For the mineral industry to utilize electrical comminution, two emerging issues identified from the research need to be address. They are the energy consumption by electrical comminution in the locked cycle treatment and the facilities scale up necessary to move this technology from the laboratory to the plant. Keywords: high voltage pulses, electrical comminution, energy efficiency, mineral liberation

Sep 1, 2012

By Shounak Banerjee, Suresh Babu Dasari, Dharmendr Kumar, Shashank Pardhikar, Beena Rai, Venugopal Tammishetti

Recent increase in steel demand has led to the increased usage of high grade iron ores. During the mining, crushing and washing of ore, huge quantities of fines and slimes (<150 µm) are generated, majority of which is dumped into tailing ponds owing to their high alumina contents (~10-15%). Due to rapid depletion of high grade iron ore, it is the need of the hour to utilize low grade iron ore fines and slimes. These fines and slimes contain high iron values assaying 45-60% Fe. Dumping these valuable resources in ponds locks enormous land space and causes environmental hazards. The constituent minerals present in Indian iron ores comprise of hematite, goethite, gibbsite, kaolinite and quartz. Our research is focused on beneficiation of iron ore slimes through selective flocculation. We use density functional theory simulations to screen the reagents and perform experiments with screened reagents to determine the experimental conditions for effective performance of the reagents. Our studies revealed that reagents like starch, guar gum and carboxymethyl cellulose exhibit excellent selectivity in high alkaline pH range. However, the higher cost of alkali makes the process economically less attractive. In the present study, a commercial reagent from NALCO Water (Hi-Tex 83570) has been explored as selective flocculant for beneficiation of iron ore slimes in wide pH range (4-11). However, the reagent was also found to be the most selective in alkaline pH range only. Full factorial design of experiments was done considering three parameters namely, pulp density, flocculant dosage and settling time. Regression models were developed for yield, iron grade, alumina grade and iron recovery in the concentrate, using experimental results. Further parameter optimization was done to achieve high Fe recoveries and low alumina recoveries. The optimal parameters thus arrived at were validated with the experiments. We were able to achieve a concentrate grade of 60.0% Fe and 5.1% Al2O3 with 68.8% Fe recovery from a feed containing of 53.1% Fe and 8.9% Al2O3. The performance of flocculant Hi-Tex 83570 was also compared with reagents starch and guar gum.

Jan 1, 2018

By S. J. Lui

Sodium oleate was an effective diaspore collector, whereas chelate collector OL2 showed certain collecting power over diaspore and nonionic surfactant OL3 showed little collecting ability. Then experiments were carried out using sodium oleate as the main collector with the addition of OL2,OL3 to study the influences on diaspore flotation, it could be seen from the experiments that accelerants had a marked influence on the recovery of diaspore, which could be raised by 10%, and the addition sequence also affected the flotation behavior: the best results could be gained when the accelerants were mixed thoroughly before adding and the best ratio of collector OL1 and accelerant OL2, OL3 stood at 30:2:1. Based on the calculation of the ingredients in the sodium oleate solution, sodium oleate reacted with surface of the mineral and formed the acid-soap polymer [HOl?Ol-] when pH was about 9. Zeta potential test showed the accelerant promoted the absorption of collector on the mineral surface, which lowered zeta potential. As could be seen from surface tension experi-ments, the addition of accelerant OL3 lowered the CMC value of OL1 solution, which was equiva-lent to raise the power of the agents. Further Infrared Ray experiments showed the co-absorption of OL1 and OL2 make aluminum oleate on the mineral surface more stable. Up till now, the mixed reagents with sodium oleate as the main collector, combined with other two accelerants had been used in the Zhongzhou concentration plant, which is the first diaspore flotation plant in China.

Jan 1, 2014

By Shen Zhengchang

Based on the flotation features of coarse particle mineral, a new type of impeller & stator unit is developed. Particles suspension state generated by this impeller & stator unit under different speeds are tested in laboratory, and critical impeller speed suit for coarse particles flotation is presented. Comparing particle suspension parameters of the new impeller & stator unit with that of KYF impeller and stator unit, it comes up that the distance between the interface of two slurry circulation channels and the cell bottom is larger in the flotation cell with new impeller & stator unit. The test results indicate that the new type of impeller & stator unit is suitable for processing coarse particles due to its good suspension capacity for coarse particles. Keywords: coarse particles, flotation, suspension, critical speed, impeller and stator unit

Sep 1, 2012

By Hong Zhong, Shuai Wang, Xin Ma

"In this paper, we report a simple and effective process for producing a surfactant mixture of O-isopropyl-N-ethyl thionocarbamate (IPETC) and 4-(tert-butyl)benzyl mercaptan (BBSH). The composite collector was synthesized via one-pot reaction of sodium isopropyl xanthate, 4-tert-butylbenzylchloride and ethylamine using tert-butyl alcohol as solvent. The whole process for the synthesis of composite collector involves neither foul smelling reagents or intermediates, nor any by-products requires special treatment for disposal, and thus can be scaled up to an industrial level. The flotation response of chalcopyrite and pyrite independently with IPETC and BBSH collectors and with their mixture (the mole ratio of IPETC and BBSH is 1:1) was assessed. The microflotation results showed that the collecting ability of BBSH was slightly stronger than that of IPETC and that IPETC was more selective collector than BBSH against pyrite, and that the composite collector displayed a stronger collecting ability toward chalcopyrite than IPETC, and superior selectivity for chalcopyrite against pyrite than BBSH. The batch flotation results showed that composite collector exhibited better performance than IPETC and BBSH. It was demonstrated that the mixing of IPETC and BBSH would give rise to a synergistic effect significantly enhancing overall flotation performance. In addition, the adsorption mechanism of BBSH on the surface of chalcopyrite was conducted by adsorption test and infrared spectrum measurement, and the results showed that the interaction of BBSH on the chalcopyrite surface was dominated by the chemical adsorption, and the formation of a strong S-M bond plays a key role in the adsorption of mercaptans on minerals surfaces. The developed flotation reagents with special preparation method is the author’s original design, patented (patent of the People’s Republic of China) and have no analogues in the world of mineral processing. (Application number 201810100107.1, ""Alkyl thioether alcohol compounds, methods for their preparation and applications thereof "", China).1. INTRODUCTION Froth flotation is an essential method widely used in the mineral processing industry to selectively separate valuable minerals from gangues[1]. Worldwide, more than 109 tons of materials are treated annually by this method with the majority being metal sulfides and oxides[2]. Nowadays, the judicious utilization of complex sulfides to meet the ever-growing demand of mineral resources gains more attention, due to the gradual depletion of deposits with high grade, making imperative the development of new high-efficiency collectors and mixtures of collectors to process complex minerals. In comparison to individual collectors, the use of mixtures has several notable benefits including lower dosage requirements, improved selectivity, rates and recovery and an increase in the recovery of coarse particles[3-9]. Moreover, in terms of cost and environmental issues, using collector mixtures can reduce the total amount of agents used, thus reducing the overall effect on the environment and economic costs without affecting the flotation performance. Therefore, the search for high-efficiency mixtures of collectors is still interesting and relevant."

Jan 1, 2018

By P. Vijay Kumar

Phosphate minerals are conventionally concentrated by flotation process using soap or soap- light diesel oil emulsion as collector. Some plants use detergents such as sodium petroleum sulfonate or alfa olefin sulfonate to enhance efficiency of soap flotation. It is reported that urea a known hydrotrope enhances flotation efficiency of soap as efficiently as alfa olefin sulfonate or linear alkyl benzene sulfonate at bench scale tests. In the present study tri sodium citrate also a known hydrotrope is tested as promoter in the flotation of phosphate mineral from Eshidiya ore.

Sep 1, 2012

By Y. Q. Yang

Jig is a kind of conventional and old gravity concentration equipment, which is mainly used in the preconcentration of medium particle fractions of low-grade nonferrous metal ore. In the past ten years, studies on jigs have made a great progress on separation of coarse and fine particle fractions. At the same time, pneumatic jigs have been widely used in processing of nonferrous metal ore. In this paper, pilot test study and commercial operation for several kinds of jigs used in Dachang con-centrator has been introduced. Dachang mining area of GuangXi province is rich in mineral resources, where many minerals exhibit various complex properties. Many elements such as Sn, Pb, Sb, Zn, S, As, Cu, In, Ag, Gd, Ag, Ga, etc, were found in the run-of-mine ore (ROM). At present, Dachang concentrator produces tin concentrate, lead-antimony concentrate and zinc concentrate. Other valuable elements get enriched and recovered in above concentrates. Dachang Mine with a mining operation history more than sixty years will end its mission on the rich ore resource exploitation. At present, low grade ores are porcessed in the concentrator, and the concentrator begins to run at a loss upon processing the low-grade and refractory ore. Heavy medium cyclones were used in the concentrator for processing 20-4mm fraction, Gongge jigs for 4-2mm fraction, and cone concentrator combined with spiral concentrator to discard the tailings of -2mm fractions. In order to minimize overgrinding, table flotation was used to recover some liberated cassiterites in a complex processing technology. Therefore, the concentrator is difficult to manage. Many years studies have shown that heavy medium cyclones and spiral concentra-tors can be replaced by sawtooth shaped wave jigs to discard 50% tailings to improve the grade of feed. And the feed was divided into rich one and poor one to minimize overgrinding of valuable cassiterites with different grinding mills. In this case, the recovery of the valuable minerals can get improved and the flowsheet was simplified. Moreover, the concentrator begins to make profit with reduction of cost. At the same time, pollution in the concentrator gets reduced and the working condition gets improved too. Sawtooth shaped wave jig was used in Changpo concentrator for replacement of cone separators and spiral concentrators to discard the tailings of -4mm fraction, and the yield of discarded tailings got improved from 30% to 50%. Grades of tin, lead and zinc in the tailings are lowered from 0.15%, 0.12%, 0.7% to 0.06%, 0.05%, 0.4% respectively, with a loss reduction of tin, lead and zinc from11%, 9%, 10% to 7.5%, 6%, 5% respectively, corresponding to the increasement of recovery of tin, lead, zinc from 52%, 50%, 55% to 56%, 56%, 62% respectively. Cost of the concentrator for processing one-ton ROM was therefore dropped from RMB155.28 to RMB119.74. Changpo concentrator lost RMB2.5 million in 2003, but it made a profit of RMB0.92 million in 2006 after the innovations. Batac jig was used in Tongkeng concentrator to discard the coarse tailings at 20-4mm, with a discarded yield of 35%, and the grades of valuable minerals got improved with a recovery above 95% for tin, lead-antimony and zinc.

Jan 1, 2014

By A. R. Hasankhoei

Water recycling is of prime importance in mineral processing due to consumption of large amount of water. This issue is vital in areas with a low rainfall such as Shahre-Babak (Kerman, Iran). Deep cone thickeners, unlike conventional thickeners, have a low diameter to height ratio where large amounts of flocculants are used to increase particles settling rates. The high bed heights (over 10 m) produce enough pressure to create a paste type underflow indicating maximum water recovery. Flocculent preparation, conditioning, and distribution along with the bed height are among the important factors affecting the performance. Four deep cones are used to recover water from the tailings of the plant. Plant data indicated that the thickener never reached the target underflow percent solids (63%) and the average underflow concentrations were between 49 and 57%. By modification and optimization of flocculent preparation and distribution methods the underflow percent solids increased by 3-4%. This translated to an increase of water recovery from 67 to 73%. This was equivalent of 53000 m3 saving in monthly water consumption. Keywords: deep cone thickener, water recovery, flocculant, copper tailings

Sep 1, 2012

By Antony Amberg, Gonzalo Saldías, Romke Kuyvenhoven, Catherine Souza, Heriban Soto, Francisco Soto

"Vizcachitas is an advanced stage copper–molybdenum porphyry deposit, fully owned by Los Andes Copper and located in Central Chile. The property contains an indicated resource of 1,038 million tonnes grading 0.37% Cu and 0.012% Mo, and an inferred resource of 318 million tonnes grading 0.345% Cu and 0.013% Mo (Coffey & Alquimia, 2014). The deposit occurs in the same geological belt as several other giant copper-molybdenum porphyry deposits including Río Blanco-Los Bronces, Los Pelambres-Pachon and El Teniente. In 2018, the original Preliminary Economic Assessment (PEA) study from 2014 was updated; this paper presents the geometallurgical testwork that was performed to support that update. The testwork focused on the metallurgical characterization of 40 DDH samples and the development of a more profound orebody knowledge by relating geological features with metallurgical performance. The scope of work included complete chemical and mineralogical QemSCAN characterization; SAG, ball mill and abrasion testing; complete rougher and cleaner kinetics including locked-cycle-test; environmental ABA and settling tests on rougher tailings. The results show that the ore can be classified as medium-hard, with a hardness that is slightly below the average for large Cu/Mo deposits in the region. A good correlation was found between lithology and breakage characteristics, implying that the specific energy consumption (kWh/t) is well correlated to rock type. The results of the flotation tests were very encouraging and did not show significant variability. An overall Cu recovery of 91% can be expected for the flotation circuit. The use of a relatively coarse primary grind size gave good final recovery and grade for both Cu and Mo, and deserves further attention in future work, as this impacts positively both energy consumption and water recovery.INTRODUCTION Los Andes Copper Ltd. is a Canadian exploration and development company focused on the acquisition, exploration and development of advanced stage copper deposits in Latin America. The company owns 100% of the Vizcachitas project in Chile, the largest copper deposit in the Americas not controlled by the majors. Vizcachitas is a copper-molybdenum porphyry deposit, located 120 km north of Santiago, in an area of very good infrastructure."

Jan 1, 2018

By John A. Rumball, Martin R. Houchin

"For gold leaching of oxide ores, the optimum cyanide : oxygen ratio is approximately 106 mg/L NaCN : 10 mg/L O2 (6.9:1 by mole). In sulphide ores, galvanic coupling of the gold with the electrically conductive sulphides significantly increases this ratio such that leaching may occur in a relatively low dissolved oxygen (DO) environment.RESULTS AND DISCUSSIONGold leaching in a carbon in pulp (CIP) and carbon in leach (CIL) circuit is driven by the supply of cyanide and oxygen, as described by Elsner’s equation (1):• 4Au + 8CN- + O2 + 2H2O ? 4Au(CN)2 - + 4OH- (1)Equation 1 suggests that the ideal molar cyanide : oxygen ratio should be 8:1, or 122.5 mg/L NaCN to 10 mg/L of DO. It is generally accepted however, that oxygen is not completely reduced to hydroxide at the gold surface, and that equation (2) better represents the gold leaching reaction (Marsden and House, 1992):• 4Au + 8CN- + 2O2 + H2O ? 4Au(CN)2 - + 2OH- + H2O2 (2)Additionally, since gold leaching is limited by either the diffusion of cyanide or oxygen to the gold surface (Habashi, 1993), then the relative diffusion rates of cyanide and oxygen must also be taken into account. Marsden and House (1992) suggest that the ideal molar cyanide : oxygen ratio is 6:1, while a more recent investigation using laboratory and plant observations (Heath and Rumball, 1998) suggested a molar ratio of 6.9:1.In practice, although a cyanide : oxygen mole ratio of 6.9:1 applies to some circuits, there are many instances when this is not the case.In sulphide ores, galvanic coupling of the gold with the electrically conductive sulphides significantly increases this ratio. Galvanically connected sulphides, and possibly carbon, provide a large surface area for oxygen reduction. As the cathode surface area increases, the oxygen concentration required to sustain the same rate of gold oxidation decreases proportionately.Galvanically connected particles may be composite particles, however they may simply be liberated sulphides in the same suspension as the gold. Particle collisions within a slurry are sufficient to provide momentary galvanic connection (Greet, 1995)."

Jan 1, 2003

By P. Fecko

The objective of the paper was application of bacterial leaching on two brown coal samples from locality Mine Druzba, seams Antonin and Josef (Sokolov brown coal basin, Czech republic). Based on the results of bacterial leaching and petrologic analyses of the given samples, it is possible to say that application of bacterial leaching gived good results. Applying bacterial leaching it is possible to remove from 34% to 47% of total sulphur and from 45% to 64% of pyritic sulphur from the coal.

Jan 1, 2014

By R. Kobialka

In the article results of experiments over jaws? linings in jaw crushers with different shaping of working surface were presented. Following sets of jaws were under investigation: immobile plain jaw and moving jaw with grooving surface. Grooving jaws have groves with circular, triangular and trapezoid cross section. In order to evaluate efficiency of comminution both the grain composition of product and the content of irregular grains were determined, as well as the size of crushing forces and process efficiency were measured. For the combination: plain jaw with grooved one, a good results were obtained as regards the grain composition of product and the content of irregular grains. Crushing forces were higher at crushing with mixed types of jaws (the one plain, the second grooved), in comparison to crushing with using both grooved jaws. Efficiency of the process was definitely higher for mixed jaws.

Jan 1, 2014