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By F. Ngoroma

Concentrators processing PGM bearing ores make use of polysaccharide depressants to reduce the recovery of the undesired naturally floatable gangue minerals, mainly silicates, present in the ore. Recent work has shown that high depressant dosages can completely depress naturally floatable gangue and thus prevent it from reporting to the concentrate. These high depressant dosages can, however, have a negative effect on the recovery of valuable minerals present in the ore by reducing the stability of the froth. In order to counterbalance the effects of depressant addition, frothers are added. It is, however, preferable to maintain independent control over bubble size and froth stability which is difficult to achieve with only one frother. An alternative strategy is, to use a blend of frothers, e.g. a weaker frother in combination with a stronger frother. Such a system allows an additional degree of freedom: changing the ratio of the two frothers, that would provide more independent control of bubble size and froth stability. This study demonstrates, through the use of batch flotation tests, how blending low molecular weight alcohols with commercially available frothers impact the solids and water recovery, as well as the valuable mineral recovery and concentrate grade in different PGM ores. Higher water and solids recoveries together with higher valuable mineral recoveries (>90% copper and >70% nickel) were obtained from tests using frother blends.

Sep 1, 2012

By Priyanka Dhar, Kurt Aasly, Hanumantha Rao Kota, Hassan Bouzahzah, Maria Thornhill

The interest in investigating the processing characteristics of mineral deposits in Norway has seen an upsurge in the last decade. One of the major areas of interest is a huge copper deposit, operated by NUSSIR ASA located in the Repparfjord Tectonic Window in the caledonides of west Finnmark. This study reports analysis of ore from the deposit for development and modifications in the flotation flowsheet for the NUSSIR ASA copper ore. The mineralogical characterization for the ore sample was achived by optical microscopy and Zeiss automated mineralogy while grinding characteristics were tested using Bond Index tests. The results confirmed the presence of Cu minerals in the form of chalcocite, chalcopyrite and bornite in the samples, which are mainly liberated in the – 105 µm size range. The majority of non-liberated copper sulphides associated with silica and the carbonates varies from 3 to 28 percent in the –250 µm samples . It is also observed that the copper minerals are uniformly distributed in all size ranges. Selective flotation of NUSSIR copper ore was performed in different size fractions with a motive to identify the correct liberation size and thus to obtain a copper concentrate meeting the quality requirements. The flotation experiments are essentially performed in two stages: the rougher and the cleaner stage. Mass balance calculations were performed showing that approximately 88 percent of copper can be obtained at the end of the process. Ultimately, overall circuit copper recoveries ranged between 83.5 to 88.1 % with a concentrate grade of 35 to 48 % Cu.

Jan 1, 2018

By Z. Hu

A complex polymetallic sulfide ore in Yunnan, China, has various valuable minerals, which are Chalcopyrite, Galena, Pyrite, Gold, Silver, and Magnetite. A reasonable new flowsheet with a bulk flotation and a flotation separation of sulfide minerals that are Chalcopyrite, Galena, and Pyrite was carried out at first stage. After that tailings were treated by low intensity magnetic separation to achieve magnetite concentrate. A high Pb concentrate assaying 60.00 percent Pb at total recovery of 75.71 percent with 40.50 g/t Au and 1390.00 g/t Ag, a final high Cu concentrate assaying 24.45 percent Cu at high recovery of 92.03 percent and a magnetite concentrate assaying 60.78 percent Fe at recovery of 33.61 percent with 18.45g/t Au and 234.99 g/t Ag, are obtained. The total recovery of Gold and Silver in Pb concentrate and Cu concentrate reached 71.63 percent and 67.32 percent, respectively. It is shown, that this new flowsheet could realize efficient recovery for all of the valuable minerals in the ore and is easy to be industrialized. Keywords: bulk flotation, magnetic separation, polymetallic sulfide ore, depressant

Sep 1, 2012

By Gautam Chandra Mondal

An attempt has been made to carry out qualitative assessment of mine water discharges from the different mines of West Bokaro Coalfields of Hazaribag district of Jharkhand, India. A total of 33 mine water samples were analyzed for pH, electrical conductivity (EC), major cations (Ca, Mg, Na, K), major anions (HCO3, SO4, Cl, NO3), and heavy metals (Fe, Mn, Cu, Zn, Pb, Cr, Ni, Co, As). The hydrochemical data has been evaluated in terms of major ion chemistry, solute acquisition processes and suitability of mine water for domestic, industrial and irrigation uses. The pH of the analyzed mine waters varies from 5.27?8.43 indicating acidic to alkaline nature of the water. The electrical conductivity (EC) values varied from 276 µScm-1 to 1598 µScm-1 for measured samples and spatial differences between the EC values reflects the wide variation in lithology, surface activities and hydrological regime prevailing in the region. The anion chemistry of the analyzed water samples shows the dominance of SO4 and HCO3 with a minor contribution from Cl, NO3 and F. The observed high values of sulphate in the mine water of the area may be attributed to the oxidative weathering of pyrites. On average chloride is contributing 5% of the total anionic balance (TZ-). Fluoride and nitrate have low concentrations and on average contributing <2% the total anions. The cation chemistry indicates that 79% of the samples are Ca>Mg>Na>K, while the 6% belong to Ca>Na>Mg>K and 1% of Ca>Mg>K>Na. Weathering of rock forming minerals and cation exchange processes normally control the levels of these cations. Concentrations of some heavy metals (Fe, Mn, Ni, Cr) are found to be well above the prescribed permissible levels recommended for the drinking water. The water quality assessment for drinking purposes indicates that most of the mine water having high TDS, total hardness (TH) and sulphate concentrations. This suggests that mine water of the study area is not suitable for direct use in drinking and domestic purposes and needs a proper treatment before its utilization. The assessment of water for irrigation uses show that the water is good to permissible quality and can be used for irrigation uses. However, high values of salinity, %Na, SAR, RSC and Mg-hazard at certain sites restrict its suitability for agriculture uses. Keywords: mine water; ion chemistry; quality assessment; West Bokaro coalfields

Sep 1, 2012

By A. Vilinska

Microorganisms have a tremendous influence on their environment through the transfer of energy, charge, and materials across a complex biotic mineral-solution interface. Recent developments in biotechnology have not only aided hydrometallurgical leaching operations but also shown great promise in mineral beneficiation processes. The adhesion of bacteria on minerals alters the surface properties relevant to flotation and flocculation of minerals. The biomodification of mineral surfaces occurs through the attachment of microbial cells, oxidation reactions and adsorption or chemical reaction with the metabolite products. Several types of heterotrophic and chemolithotrophic bacteria have been successfully applied in flotation and flocculation processes for the last two decades. Al-though the potential of microorganisms in minerals beneficiation has been realised by several re-searchers from their laboratory investigations, the studies were mostly confined to pure mineral systems and there is hardly any sincere effort to apply the methodologies on ores. This paper presents a brief summary of the literature in bioflotation and bioflocculation, and attempts to outline new dimensions of research for a practicable application of this technology in mineral industry.

Jan 1, 2014

By John Jiang, Brian R. Hart, Stamen S. Dimov, Aparup Chattopadhyay, Barun K. Gorain

"This paper presents a systematic approach to metallurgy diagnostics using an integrated gold deportment methodology developed for complex refractory gold and copper-gold ore bodies. Quantification of gold deportment for these ore bodies is a challenging task due to reasons such as lower grades, high variability of visible and invisible gold content in different sulphides and iron oxide phases, significant presence of disseminated and composite carbonaceous matters along with associations of various copper sulphide phases. Some case studies are presented in this paper to demonstrate the value of a high confidence gold deportment methodology in developing insights for problem diagnostics and to identify opportunities for metallurgical improvements. A holistic approach involving different fields of expertise is critical for successful development and delivery of solutions for complex ore bodies.INTRODUCTION Studies were initiated on various ore complex ore and also on samples representing various process streams. These complex copper-gold single refractory, double and triple refractory gold ores are mainly composed of silicates and/or carbonates with moderate amounts of clay and mica, along with minor amounts of sulphides and organic carbonaceous matter. Variable proportions of visible gold and “invisible gold” (sub-microscopic gold) were noted in different mineral phases for various ore types and process stream samples. Invisible gold commonly occurs as solid solution or as colloidal-sized particles in different sulphides (pyrite, arsenopyrite, pyrrhotite, chalcopyrite and galena) and other phases (including hematite, magnetite and goethite) for different refractory ores. The dominance of invisible gold and presence of highly preg-robbing along with finely disseminated carbonaceous matters adversely affects gold recovery in flotation and leach circuits for most of these double and triple refractory ores. This paper discusses applications of an integrated gold deportment technique developed for different types of gold and copper-gold ores, namely, complex copper-gold, double and triple refractory gold ores (Chattopadhyay and Gorain, 2014; Chattopadhyay et. al., 2016). Various process streams from flotation and gold leaching circuits were investigated. Different concentrates and tailings samples from flotation circuits whereas feed and discharges from pressure oxidation (POX) and carbon-in-leach (CIL) residues were used from gold processing circuits."

Jan 1, 2018

By M. P. Krasteva

The froth flotation process for separation of mineral ores depends on the establishment of care-fully controlled froth. The formation of very stable froth in the flotation circuit is a problem that may occur in many plants, resulting in down-time, low quality and grade of final product and considerable expenses. Froths build up on the top surfaces of thickeners, tanks and flotation cells until they overflow, or until the efficiency of the circuit is impaired. A similar problem exists in Assarel concentrator, Assarel-Medet PLC, Bulgaria. Copper and copper-pyrite ores are dressed in Assarel concentrator. They are characterized with variable and complex mineral and physical composition. During the flotation cycle, resilient and difficult to break-down froth is formed, which subsequently impedes the process of thickening and clear overflow obtaining. Due to this problem continuous sampling in the cycle of thickening was conducted. The mineralogical, chemical composition, particle size distribution and solid phase content of the products were determined. It was established that the solid phase of the froth build up on the top surface of the thickener differs considerably from this one of the thickener underflow. The data clearly indicates that a separation process takes place on the top surface of the thickener ? fine particles of chalcopyrite are concentrated in the froth. The role of chemical reagent addition in the break-down of the flotation froth is investigated in terms of surface chemical phenomena involved in the stabilized froths. Measurements of the coper minerals wettability and surface tension at the air/liquid interface were performed. The surface active agent AERODRI® dewatering aids were laboratory tested. Bench-scale froth collapse tests were conducted. Reagent addition into pulp-froth system promotes and leads to a bubble coalescence, an improvement of the wetting of the mineral particles and a decrease of the surface tension at the air/liquid interface. The results of the laboratory experiments showed that the presence of the surface active agent leads to considerably decrease of the froth stability and the destruction of the deleterious froths build up on the top surface of the thickeners in Assarel concentrator.

Jan 1, 2014

By Vladimir F. Skorokhodov, Nikolay N. Melnikov, Svetlana P. Mesyats

"Among the problems of the civilization development, a problem of interaction between man and natural environment can be highlighted. In the twentieth century the human transforming activity had got scales of geological processes and defined the contradiction between the goal to increase the quality of human life and possibilities of the natural environment. Last twenty-five years after the World Summit on the Environment (1992) indicate that the development of civilization is still based on receiving super profits from the natural resources exploitation. This statement is confirmed by economy globalization rates, growing contradictions between consumption and production, depletion and degradation natural environment. A new technological order is formed at the time of growing world population, technological capacities, organizational complexity, from one side, and global scales of geo-resources consumption, on the other side. Sciences, determining the further civilization development, should take on the task to change the social worldview, since the preservation of human population consists in remediating and maintenance of biosphere functions as a regulator of ecological balance. The new worldview in the geo-resources exploitation is based on the Ecological strategy of mining development, which consists in reducing mining-induced loading on natural environment while increasing efficient mineral production and processing, and providing for a comprehensive solution of tasks on mineral deposit development. One of strategic trend of mining development is to increase complexity and completeness of useful component extraction from ore and mining deposits while reducing wastes and decreasing their stockpiled volumes. The implementation of the ecological strategy has shown that the future is determined by reduction of the environmental impact while improving the efficiency of mineral mining and processing.INTRODUCTION The global nature of environmental problems caused by the scale of consumption of natural resources, huge amounts of waste, and intensive man-made impact on the environment requires a revision of the strategy for the natural resources development. Many existing technologies are ineffective in achieving the ultimate goal. Direct output in the raw materials - the end product technological chain rarely exceeds 10%, which implies a huge amount of work to move the soil. In addition, the feature of scientific and technological progress at the present stage is the growth of power-to-weight ratio."

Jan 1, 2018

Large quantities of electrical and electronic equipments are discarded at the end-of-life (EOL) in different industries and house hold applications. Their disposal is creating a challenging environmental problem due to the presence of hazardous metals and non-metallic materials such as epoxy resins and plastics including brominated flame retardants etc particularly in printed circuit boards (PCBs). The recovery valuable metals and separation of hazardous materials from discarded PCBs will not only conserve the resources but also mitigate the environmental pollution. From a recycling point of view for a sustainable society, the studies have been carried out for the recovery of metal values from EOL-PCBs of DVD video players (DVD-PCBs) and vacuum cleaners (VC-PCBs) using physical beneficiation techniques. The concentration of the metals was found to be 43 wt.% and 30 wt.% in DVD-PCBs and VC-PCBs, respectively. Both the PCBs samples were ground in a hammer mill after cutting and their size analysis was carried out. The liberation of the metallic and non-metallic fractions was investigated under the microscope for different size fractions. Subsequently, froth flotation and pneumatic air separation studied were carried out to enrich the metallic constituents. The studies showed the enrichment of metals in coarser particles (-1000 +150 µm) and non-metals in the finer particles -150 µm following mechanical recycling process. A grade of 90 % with 75% recovery was achieved by froth flotation, but lower grade and recovery of 75% and 65% respectively were obtained by pneumatic separation with -1500 µm powders for DVD-PCBs. A grade of 86% metal was obtained by froth flotation with 76% recovery in the case of VC-PCBs. The lower grade of 65% with almost same recovery was achieved during pneumatic separation studies due to lower concentration of metals in VC-PCBs. The studies also showed that the froth flotation is an efficient process for enrichment of metals from both the samples. The process is environmental friendly as no chemicals are employed during entire processing. The higher recovery and grade of metal is expected to be obtained on a large scale beneficiation process.

Sep 1, 2012

By Hamid-Reza Manouchehri

"The triboelectric charge attributes of feldspar, quartz and wollastonite minerals, after contacting different triboecharging medium made of different materials, were considered. Their charge acquisitions by different size fractions of minerals were monitored and accordingly their energetic work function values were estimated. Moreover the separation behaviours of these minerals through the electric field of a laboratory free falling separator were determined and the effects of some chemical reagents on separation their separation characteristics were studied.Finally an attempt was made to translate the findings from single mineral systems to a complex silicate ore, containing quartz, feldspars, wollastonite and some other silicates. The results show favourable prospect to apply the triboelectric separation technique for beneficiation such a complex raw material."

Jan 1, 2003

By X. J. Lu

Purified Na-montmorillonite samples were used as the starting materials to prepare organically modified montmorillonites (OM), and a series of OM samples were prepared by intercalation of al-kyl quaternary ammoniums with different alkyl chain length. The interlayer spacing (d001) of the OM was determined by small angle X-ray diffraction and its gelating performance was characterized by measuring the viscosity of OM/dimethylbenzene mixture. The effects of alkyl chain length, dosage of alkyl ammonium, intercalation duration and layer charge of the starting material on the OM structure and gelating properties were investigated. According to the results, the adsorption quantity of the alkyl ammonium is dependent on the hydrocarbon chain length, the dosage of the alkyl ammonium and the retention time. The adsorption quantity of the alkyl ammonium increases with the chain length and the dosage, and extra adsorption more than the CEC of the montmorillonite sample was observed under the dosages of more than 1.3 CEC. The interlayer spacing (d001) of the OM shows a dynamic variation with the dosage and the retention time, and super interlayer spacings greater than the length of the alkyl ammonium were observed under larger dosages and shorter retention times. However, the gelating performance of OM does not follow the variations of the adsorption quantity of alkyl ammonium, an optimum viscosity value of OM/ dimethylbenzene gel was observed with the moderate adsorption of the alkyl ammoniums. Furthermore, the layer charge plays an important role on the gelating performance of OM. The OM synthesized by the starting material with lower layer charge shows better gelating performance in the dimethylbenzene solution.

Jan 1, 2014

By S. Narra

The importance of bio-products production is enhanced with the abundance and renewability of ligno- cellulosic biomass in comparison to the depleting fossil fuels especially in producing environment friendly energy. Lignin is obtained as a sludge residue from the pulp and paper industries as well as from the bio- ethanol /bio-gas production plants. Lignin is a renewable fuel with a high heating value equivalent to anthracite coal, low ash content and hydrophobic properties. The extracted lignin in paper and pulp mills is usually burnt at the mill directly to cover the energy production costs of the mill. The efficient utilization of lignin can reduce the percentage of lignin sludge used for energy production in comparison to the present situation. Presently the lignin is burnt /incinerated as sludge with minimum of 30 to 50 % moisture content. This high moisture content reduces the energy efficiency and simultaneously utilizes more amount of lignin sludge in producing the required energy. This paper explains a possibility of integrating sludge-pelleting techniques in paper and pulp mills. The integrated sludge-pelleting techniques would lead to an optimal utilization of lignin for energy and would simultaneously save the lignin resource for material utilization. The sludge pelleting process solves also the problem of handling, storage and explosion risks of lignin when compared to the present situation.

Sep 1, 2012

By I. Yelkin, Erico Tabosa, Alex Jankovic, R. Hayashida, R. Faveere

"The mining industry faces growing challenges from more complex and lower grade deposits, rising costs, limited energy and water availability, and increasing societal pressure to operate more sustainably. Mining operations need to be more efficient, not just to reduce environmental impact, but also to remain economically viable.To maximize profitability and sustainability, existing operations and new projects must consider integration and optimization of all stages of production. A mining operation is essentially a series of inter-connected processes, with the performance and outputs of each stage affecting the subsequent ones. Optimizing stages in isolation can result in sub-optimal overall performance.The industry has long recognized the benefits of holistic optimization using the Mine-to-Mill concept, and there are many well documented successes. However, it is increasingly common to observe operations simply increasing explosive consumption in the mine and expecting optimization of the entire value chain (mining and processing). For true holistic optimization, blast intensity is not necessarily increased, but rather adjusted to best suit the requirements of the different types of ores treated, the circuit configuration and equipment, installed comminution power and the downstream beneficiation processes. It is a fully integrated effort with optimization of many aspects in the mine, comminution and separation processes.To be successful, optimization of the production chain from mine to process requires a site-specific, structured methodology supported by extensive ore characterization, auditing, surveys, data analysis, mathematical modelling simulations and a cost / benefit analysis. Following this methodology, optimization strategies are rapidly identified and implemented considering mine and plant constraints. Management needs to set up appropriate KPIs and site personnel need to be trained for the new operating strategies to be successfully incorporated into site practices and procedures in the production environment. This will ensure the benefits are achieved and maintained. This paper describes the methodology employed by Hatch to improve overall efficiency and profitability from mine to process. Two case study examples at Russian gold operations and benefits achieved are presented."

Jan 1, 2018

Ca-containing gangue minerals such as Fluorite, Calcite have same surface activity point--calcium ions and approximate floatability with scheelite, it is difficult to achieve good dressing index of rough concentrate of scheelite. Mono-mineral experiments and ore tests indicate that, according to mineral composition, gangue minerals can be inhibited selectively by adopting suitable regulators, then the separation of scheelite from gangue minerals can be realized effectively. Mechanism analysis was taken by zeta potentials measurements and FTIR tests. Good dressing indexes are also obtained in practical ore tests and industrial tests. Keywords: scheelite, fluorite, calcite, regulator, flotation separation

Sep 1, 2012

By V. E. Vigdergauz

The work presented shows results of electrochemical study of pyrite hydrophobicity evaluated by air bubble induction time (IT) measurements. On the basis of measured IT?s an average thickness of the thin liquid film prior to its rupture has been evaluated, which confirms long-range character of the interactions between air bubbles and hydrophobic surfaces. Obtained data are discussed in the frame of recent studies of structures of solid-liquid interface based on molecular dynamics simulations and results of surface force measurements.

Jan 1, 2014

By Xianjun Lu

This paper presents gold occurrence investigations on the altered rock gold deposit from Jiaodong area of China, and comparisons of gold occurrence in the ore samples from different mining levels. According to the results, the chemical and mineral compositions of raw materials from different mining levels are quite similar. However, the relative content and grain size of gold minerals are quite different between the two mining levels of -130m~-340m and -550m~-650m. In the ore of upper mining levels of -130m~-340m, electrum is the dominant gold mineral and accounts for about 80% of the total gold minerals, while native gold is minor and accounts for about 20%. As for the ore of deep mining levels of -550m~-650m, the major gold mineral shifts to native gold which accounts for 67%, while the ratio of electrum drops to about 33%. Coarser gold grain size was observed in the upper mining level ore with a mean size of 33.05µm while the gold grain size was much finer in the ore of deep mining levels with a mean size of 22.85µm. Furthermore, the gold mineral associations also show different patterns between the upper mining level samples and the deep mining level samples. Of the three observed gold association types such as inclusion gold, fissure gold and interparticle gold, more inclusion gold was found in the ore of deep mining levels. The inclusion gold accounts for 62% in the ore of deep mining levels, while that in the ore of upper mining levels accounts for about 56%. Further study revealed that the dominant gold associated minerals are pyrite and sulphides and only a small amount of gold is associated with quartz and silicates. It was shown that the altered rock gold ore from Jiaodong area can be regarded as a free milling gold ore, but the processing parameters should be optimized for the ores in different mining levels according to the different gold occurrence. In addition, it was predicted that enhanced gold liberation is necessary for the ore in deep mining levels.

Sep 1, 2012

By Y. M. Zhao

The dry coal preparation technology based on air dense medium fluidized bed is an innovative dry highly efficient technology of coal by introducing fluidization technology into beneficiation.. A modularized 40-60 tones/hr system (KZX-40) with an air dense medium fluidized bed separator was established. The construction cost of the modularized system is only 1/3 of the traditional wet heavy-medium coal preparation plant construction cost with the same capacity, and the consumption of dense medium can be reduced by 50%-60%. The footprint and volume of the system are decreased by 75% and by 89.81%, respectively. These facts show the improved intensity, efficiency and economy of modularized coal preparation technique. The modularized KZX-40 system can be used to separated 50-6 mm coal over a separation density range of 1.3-2.2g/cm3 depending on the variation of <1mm fine coal content. The separation efficiency of the system was investigated at low and high separation densities by float-sink experiments. The partition curve of the products at low separation density shows that the separation density (d) is 1.33g/cm3, and the probable error (E) value is 0.05g/cm3. Using 50-6mm coal with an ash content of 55.35% as feedstock, at a high separation density of 1.61g/cm3, the clean coal with an ash content of 14.67% and the tailing with an ash content of 71.26% are produced with an E value of 0.06g/cm3. It is clear that the modularized KZX-40 system is suitable for separating 50-6mm coal effectively. During the dry coal preparation process, the dust is removed by the bag collector and recycled back into the separator. So the system has the advantages to work without environmental pollution and water. The modularized system greatly reduces the construction and operating costs and decreases the area and volume required, compared with wet dense medium system. The system is applicable to the coals located in arid regions and also to the coals that tend to slime during wet separation. Keywords: modularized, KZX-40, fluidized bed, beneficiation

Sep 1, 2012

By V. A. Luganov

The processing of pyrite concentrates may be accomplished with a preliminary enrichment due to withdrawal of iron sulfides from initial concentrate. The withdrawal of iron sulfides is possible with the help of magnetic separation when the magnetic iron sulfides (pyrrhotites) separate from non-magnetic fraction?the sulfides of non-ferrous metals. The conversion of non-magnetic pyrite to magnetic pyrrhotites of adjusted structure occurs because of roasting with the withdrawal a part of sulfur. The resultant pyrrhotites are strong ferromagnetic with hexagonal structure. This paper contains results of studying magnetic properties of pyrrhotites, findings of the de-composition of initial pyrite with the consequence homogenizing of product and hardening of product of decomposition in liquid nitrogen. Define the type of pyrrhotites super lattice structure, was established that at increasing of sulfur contention the magnetic properties of pyrrhotites are change ? pyrrhotite begin evince the properties of antiferromagnetic material and magnetic susceptibility of material is interruptive changing from 0 to 1.7×10-3~1.9×10-3 SI units/g system. The paper contains results of technological researching of pyrrhotizing-magnetizing roasting of pyrite concentrates in different condition: in unoxidizing, with the decreasing contention of oxygen and in autogenous regime in air atmosphere. Established that the magnetic susceptibility of products depend of pyrite degree dissociation and achieve 2×10-3~3×10-3 SI units/g system at 40%~45% desulphurization. Defined the conditions of steady regime autogenous roasting, at resultant products possess coefficient of magnetization, and this can be used magnetic separation for separating ferromagnetic pyrrhotites from gangues and non-magnetic sulfides of non-ferrous metals. This technology of pyrrhotizing roasting is recommended for effecting in industrial condition. The initial materials and products of roasting subjected to chemical, thermogravimetric, Moss-bauer spectroscopy and X-ray analysis, defined the magnetic properties.

Jan 1, 2014

By B. Rezai

Impeller speed and air flow rate are two influence parameters on coarse particles flotation and collision and attachment angles. So, in this research recovery of quartz particles at four diameter classes carried out and collision and attachment angles investigated. It is found that maximum flotation response was observed at Impeller speed of 1100 rpm and 15 L/h air flow rate. For either more quiescent (Impeller speed<1100 rpm) or more turbulent conditions, flotation recovery decreased steadily. Furthermore, amount of attachment probabilities is calculated using suitable equation. According to this study, with decreasing particle size, air flow rate and impeller speed, probability of attachment increased and with increasing contact angle, probability of attachment increased. For various air flow rates, impeller speed and particle size, collision angle has been calculated. Maximum collision angle obtained at with 15 L/h air flow rate, particle size of 256 µm and impeller speed of 700 rpm and minimum collision angle obtained at with 45 L/h air flow rate, particle size of 545µm and impeller speed of 1300 rpm. In this study, maximum attachment angle, , was around 75 L/h air flow rate, particle size of 256 µm, contact angle of and impeller speed of 1300 rpm and minimum attachment angle was with 15 L/h air flow rate, particle size of 545 µm, contact angle of and impeller speed of 1300 rpm. ?82.72 ?64 cr??33.39 ?90 ?13.0 ?60

Jan 1, 2014

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

"With the trend of increasingly more mineral resources turning low-grade and refractory, more and more new ore bodies being developed worldwide are more finely grained, which drives the rapidly development and application of techniques related to tower mills (vertical spiral stirred mills). However, the lacking in fundamentals of fine grinding, as well as standard procedures for equipment selection and scale up, seriously restraint high efficient application of tower mills. Taking grinding media motion characteristic and grinding intensity as a breakthrough point, this paper studies mechanisms behind how critical parameters affect grinding efficiency of tower mill, including ratio of screw pitch and diameter, agitator rotation speed, grinding media size. Several sets of orthogonal test are conducted on the quartz ore using the grinding system of KLM-3 tower mill. All the tests are under the same character of feeding mineral and undergo the consistent sampling for at least 60min grinding time. The input power is measured by a torque measurement system and the grinding products are analyzed by the laser particle size analyzer. The test results show the influence of parameters on grinding efficiency. Among the three important parameters, the effect of grinding media diameter is the biggest, followed by the agitator tip speed, and finally the ratio of screw pitch and diameter. For the different particle size of grinding products, the best combination of grinding parameters is different, with the mineral size becoming finer, the ratio of screw pitch and diameter become smaller, the diameter of grinding media become smaller, while the agitator tip speed does not change too much. The conclusions of the study help us to improve the grinding efficiency of the tower mill, to assist in the selection and optimization of working parameters, establish new scale up method on the basis of grinding model and eventually provide theoretical basis of rational selections of structural and media physical parameters within tower mill."

Jan 1, 2018