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

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

Jan 1, 2018

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

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

Jan 1, 2018

By Jacek Kolacz

A new sensor based sorting system has been developed, based on complex image analysis, where an image texture and a shape pattern is considered for identifying particles for separation. The sorting system employs different images generated by visual light and X-ray to provide maximal information about processed particles. Application of X-ray makes it possible to analyse the internal structure of the particles, which provides a 2D image with complicated texture, however, which contains valuable information. The advanced system for the texture and the pattern recognition is applied to analyse these images simultaneously, to provide the required identification of the particles for efficient separation. The mathematical models applied during identification and separation, are assisted by high speed calculations being specially optimised for this kind of process. This allows sorting with high capacity and high accuracy, which is critical for practical applications in mineral processing. The paper describes a number of tests during sorting of iron ore and coal with high separation efficiency.

Jan 1, 2014

By C. S. Gundewar

About 90% of the barytes produced the world over is used for oil and gas drilling as weighting agent in drilling mud to control pressure, prevent blow out and provide lubrication. This is because of its unique properties like high specific gravity, water insolubility and intentness. India is one of the leading producers and exporters of barites. The Mangampeth Baryte deposit in Cuddapah district of Andhra Pradesh, India being the largest single deposit in the world having a reserves of about 80 million tonnes. Approximately 50% of the total reserves of grey barites of Mangampet deposit assays less than 92% BaSO4, the minimum stipulated grade for oil and gas drilling industries. To reach and recover the high grade barite, the overlying low grade has necessarily to be mined out and removed. At present this is being stacked separately at the mine site involving lot of labour and transport cost. Considerable barites is contained in the dumps adversely affecting the conservation and creating lot of environmental hazards. IBM being the premier organization in India in the field of conservation of minerals and environmental protection in mining has recognized the importance of adverse effect of these huge dumps at site. The Ore Dressing Division of IBM, Nagpur has characterized these dumps and developed the flotation process on a sample assaying 66% BaSO4 and 23.3% SiO2. The flotation concentrate obtained assayed 93.7% BaSO4, 2.38% SiO2 with BaSO4 recovery of 80% and meets the requirement of the oil industry. The flotation concentrate being non-wetable, can not be used as such as weighting agent, and hence the collector coating on the concentrate was removed either by acid treatment or heating to make it water wetable. The concentrate was 92% -325 mesh and having a specific gravity 4.3. The barites concentrates so produced meets the size, grade and specific gravity specifications required for use in oil drilling industry. Apart from the financial benefits the process augurs well for the commercial exploitation of these huge dumps in terms of (1) additional recovery of these valuable minerals and conservation, (2) reduction in dumps value, (3) improvement in environment and offering an excellent potential for export.

Jan 1, 2014

By X. M. Yu

A large amount of polluted sludge is produced by a nonferrous metal factory after treating waste water with lime/ferrous salt. The concentration of arsenic in the dried sludge is high to 5.84%, a toxicity test is taken on the sludge according to GB5085.3-2007 and the extraction content is 15.75mg/L, which surpasses the arsenic extraction standard [As]=5mg/L, the sludge is categorized as hazardous waste. If put outside without disposal, it would be very harmful to environments. Here we report an optimum protocol to extract arsenic; S2- alkaline liquor is utilized to treat the arsenic sludge. At 85?, 10L 7% S2- liquor is added into 1kg dried sludge and the resulting mixture is stirred for 120min at 250r/min, then separated by centrifugation and the compressed waste residue dried naturally. The average arsenic content is 1.40mg/L, lower than GB5085.3-2007 Standard and arsenic-free residue is consistent with GB18598-2001 Standard, which can be bury safely. The extracted arsenic is transferred into copper arsensite for use as addictive in copper electrolysis and the waste water can be recycle after calcium is removed.

Jan 1, 2014

By Arkady Senchenko, Yury Kulikov

"Basic theoretical grounds of the methods applied for crushing and grinding parameters determination according to international standards are given in this paper. Statistical data about crushability and grindability research are shown. The potential relationship between the values of Fred Bond Work indices and John Starkey indices (Crushing index, Ball mill index, Rod mill index and AG/SAG index) are discussed in this paper. In order to establish correlation between the crushability and grindability indices the analysis of over 2 500 tests for 165 deposits located in different parts of the world was performed. The relationships among different types of energy consumed for crushing and grinding were determined. A method for preliminary estimation of energy consumption in semiautogenous + ball mill grinding circuit is suggested for its application in preliminary technological solutions development and technical-and-economic assessment."

Jan 1, 2014

By Gideon Chitombo

"Mining is a "continuous" process of dependent breakage and materials handling stages, from the initial breakage of the in-situ rock, extraction from the pit or underground, and finally to the surface stockpile and downstream processing. Over time, underground and in-pit mining activities diverged into two separate disciplines, each using a variety of in-situ breakage techniques and surface activities, with processing techniques dependent on mineralogy or grades. This artificial separation of underground and open pit activities was exacerbated when the two became increasingly managed as separate cost centres rather than as an integrated unit. Mass mining essentially began in 1903 when metallurgist Daniel Jackling initiated the world’s first open pit, mining system at the Bingham Canyon porphyry copper deposit in Utah. The term mass mining has since been construed to mean large open pits and cave mining methods, including their variants. These methods are largely non-selective, involving the mass extraction of a deposit irrespective of the uneven distribution of grade and mineralogy. The advantages of mass mining have historically applied mostly to low grade, large scale deposits. With the depletion of mineral reserves closer to the surface, however, new deposits are deeper, lower grade and mixed with more impurities. These and other factors make extraction more difficult and costly. Mass mining is moving rapidly into a new and less certain environment where revolutionary changes are required to effectively deal with future challenges which are technical, economic and environmental (licence to operate). This keynote address presents current initiatives being considered for the next generation of both underground and surface mass mining systems in order to significantly reduce lead times and mining costs (CAPEX and OPEX), substantially increase productivity and meet license to operate requirements. The address is designed to solicit discussion on how better integration of mining and processing can become a platform for these next generation of mass mining systems and can also help the industry deal with the future challenges."

Jan 1, 2014

By W. Z. Zu

In proved reserves of vanadium-containing titanomagnetite in Panxi, China, iron grades of ores were 50% ~ 15%. China?s metallurgical industry departments defined the iron ores containing 50% ~ 20% TFe as exploitable resources and the extreme lean iron ores containing 20% ~ 15% TFe as temporary unexploitable resources, the extreme lean ores were as waste rejected into waste dump in mining process. This paper researched process mineralogy of the extreme lean ores, adopted mineral processing technology responded to the properties of the ores to treat the ores and obtained quality vanadium-iron concentrate, titanium concentrate and sulfur concentrate, therefore successfully utilized the extreme lean ores, changed the ores from waste resources to exploitable resources.

Jan 1, 2014

Flinders Power, formerly NRG Flinders, is considering the possible use of low rank coal from Lake Phillipson, South Australia (SA) in its power stations at Port Augusta, SA. Typically, this coal contains about 35% moisture and 10% ash. Unfortunately, it also contains high levels of sodium (1% Na) and chloride (0.95% Cl) with a Na2O level in ash of 18.9%. Such levels cause serious problems during coal combustion, making the use of as-mined coal impractical for power generation. This paper describes the development of an aqueous leaching technique to remove 90% of the sodium and chloride and to yield a product with a Na2 O level in ash of less than 3%. Small-scale agitation leaching tests with good quality tap water at ambient temperatures showed that the coal needed to be crushed to minus 5.6 mm to obtain maximum removal of water-soluble sodium and chloride in 30 min. Leaching kinetics, but not the ultimate removal of salt, were enhanced by the use of higher temperatures (up to 150°C), but this was deemed uneconomic. Varying the pulp density between 20% and 50% had little effect on extractions and there was no benefit in multiple stage water washing. The best results by water leaching were 69%~74% extraction for sodium and 95%~97% for chloride, meaning that the sodium removal was well below the target level. From SEM examinations of the leached product it was concluded that the remaining sodium was organically bound to the carbon atoms in the coal. Further tests using aqueous solutions containing cation exchange additives such as calcium chloride (CaCl2) or ammonium chloride (NH4Cl) or sulphuric acid (H2SO4) showed that significantly enhanced sodium extractions were possible and target specifications were met. Two options, namely a single-stage and a two-stage leach, were then investigated. In a single-stage leach with additive, minus 5.6 mm coal was leached at 33%~50% solids for 30 min at ambient temperature and then filtered and washed with fresh water. This gave a sodium removal level of about 81% and a Na2O level in ash of about 5%. These levels do not quite meet tar-get specifications. In a two-stage leach, the coal was first leached with water alone without an additive as in the single stage leach, and the washed residue re-leached under similar conditions for about 5 min with an additive (CaCl2), and then filtered and washed. This gave a cumulative sodium removal of 96% and a Na2O level in ash of 1.4%~2.4%. These levels are well within target specifications.

Jan 1, 2014

By E. Barsky

Physical principles of two-phase flows with a polyfractional solid phase have not received a sufficient theoretical interpretation as yet. Two-phase flows in the separation mode with a counter-flow of particles are even more complicated. Only statistical methods give an insight into general regularities of such processes. These processes can be interpreted best by analogy with the statistical model of an ideal gas developed by L. Boltzmann, although here a number of difficulties arise. The notion of a statistical system for such flows is substantiated. A mathematical estimation of a statistical system is presented. New notions are introduced, namely, potential extraction of a system and lifting factor. A relationship having the physical meaning of entropy is derived for a two-phase flow in the separation modes. The connection of this new entropy with flow parameters, such as the number of particles, separation factor and chaotizing factor, is established. Properties of this entropy are analyzed, as well as the analogy and difference between this entropy and Boltzmann?s entropy. The notion is formulated and the definition of the chaotizing factor of a process is suggested. In the framework of a statistical approach to two-phase flows in the separation mode, the notion of flow mobility has been formulated. Principal regularities of mass transfer in zone/apparatus sys-tem are analyzed. Principal ideas of a cellular model of the process are formulated, and main relationships for its description are derived. Proceeding from the cellular model, a dependence describing the degree of fractional separation of a narrow size grade is found. The analysis of this dependence makes it possible to reveal the crucial role of the Froude criterion for gravitational separation processes. It is found empirically that this parameter is a basis for the affinization of separation curves (Barsky E, Barsky M, 2006; Barsky, 1980).

Jan 1, 2014

By Q. X. Li

The state discharge standard for arsenic-containing wastewater which is the first kind of pollution is less than 0.5 mg/L. In fact, in a certain company, the acidic arsenic-containing wastewater in non-ferrous smelting was as high as 860 mg/L, which is far beyond the state discharge standard. Obviously, the direct release of this wastewater without further treatment would result in great hazards to the ecological environment. To aim directly at the characteristics of acidic arsenic-containing wastewater, in this study, two steps of treatment including oxidation-flocculation and removal fluoride by mixing alkaline neutralization were suggested. Through analyzing various influencing factors in treatment effects, the optimum technical conditions were obtained. The sediments after treating were recyclable and the secondary pollutions can be avoided. Moreover, the results also show that, all indexes of the effluent after treating are lower than the First Grade Standard of Integrated Wastewater Discharge (GB 8978-1996). This novel method has advantages of short flow sheet, easy operation and low cost.

Jan 1, 2014

By Kari Niiranen

LKAB (Luossavaara-Kiirunavaara AB) is operating iron ore mines, concentration plants and pelletizing plants in Northern Sweden. The largest of the apatite magnetite deposits and the mines are Kiirunavaara with annual production rate of approximately 27 Mt crude ore underground. LKAB produces two varieties of pellets: blast furnace pellets and direct reduction pellets (LKAB DR Oxide Pellets). Meanwhile the concentration process in a sequence of the low intensity magnetic separation (LIMS) and flotation at the concentration plant. In spring 2007 there were noticed great fluctuations of SiO2 grade in the crude ore. The high SiO2 grade is particularly problematic in the case of direct reduction pellets. In consequence, a project was started (called Silica in the Mine) to define exactly the problem related with silica and to find out, if possible, the reason for the great fluctuation of SiO2 grade in the crude ore going to the processing plant. A further target of this project was to develop a simplified method at the laboratory scale, to predict SiO2 grade in the magnetite concentrate in the future, but also predict the physical properties of the ore with respect to mineral processing. The essential stage of systematic characterization of the ore body for mineral processing properties is the estimation and simulation of different parameters from the laboratory scale to the large scale at the concentration plants using empirical data collected at the mineral processing by LKAB in Kiruna. Further a target was also to find useful physical parameters for mineral processing and implant those parameters into the existing geological 3D-model of the deposit. This information will be used for making prognosis of the future mining and the quality of the crude ore. It will also give better control and improve the production planning in the mine and the performance at the concentration plant in Kiruna concerning the decrease of the SiO2 grade of the magnetite concentrate.

Sep 1, 2012

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 K. Hori

In this study, the determination of optimal conditions for jig separation has been investigated with a TACUB jig separator. The TACUB jig, from which a Batac jig originated, is a useful gravity separator that is effective to separate crushed solid wastes as well as coarse ores. A mixture of crushed polyethylene (specific gravity 1.3) and polyvinyl chloride (specific gravity 1.5) was separated by a batch TACUB jig by varying the frequency (wavelength) and the amplitude (pulse stroke length). It was found that the sample particle layer in the separation chamber was fluidized without turbulence by the rising water pulse resulting in the separation. However, a too strong water pulse reduced the efficiency of the separation of the particles. The results indicate that the specific velocity of the rising water is necessary to fluidize the particle layer without turbulence to separate the particles. The expansion ratios of the thickness of the particle layer in rising flows were measured in a cylindrical column. The pressure losses by the particle layer were calculated from the expansion ratios and the velocity of the rising flows by Ergun?s equation. The curve of the pressure loss vs. the velocity of rising flow showed a maximum point corresponded to the point of fluidization. The velocity of a rising flow on the point of fluidization provided the optimal separation condition.

Jan 1, 2014

By Jun Xiao, Yucai Zhou, Yanhong Dong, Daixiong Chen

"In this article research on the mineralogical characteristics and beneficiation process for a copper molybdenum deposits in Heilongjiang province of China has been carried out. Chemical analysis, X-ray diffraction(XRD) and Quantitative Evaluation of Minerals by SCANning electron microscopy (QEMSCAN) were conducted on samples. The bulk analysis results showed that: (1) Comprehensive recovery and separation of molybdenum & copper minerals was feasible by the flowsheet of first copper-molybdenum mixed flotation after grinding the ore samples to 61.88% -74µm and then separation flotation of copper and molybdenum after regrinding the Cu-Mo mixed concentrate to 83.26% -38 µm. The results highlight relationship between mineralogical characteristics of ore and comprehensive benefication method. (2) the combination of "" Sodium sulphide and sodium thioglycolate "" reagents are effective inhibitors of copper-molybdenum mixed concentrate, their selectivity performance is better than that of single reagent. Good flotation indexes were gained that might be directive experience to similar cases. KEYWORDS Mineralogical characteristics; molybdenite; chalcopyrite; flotation separation; inhibitor INTRODUCTION Copper and molybdenum metals are widely used in the field of metallurgy, aerospace, national defence, etc. Copper –molybdenum sulphide ore is an important source of copper and molybdenum metals. At present flotation is still the preferred methods to deal with the copper-molybdenum sulphide minerals (Yin, Z., Sun, W.et al. 2017; Ansari, A., & Pawlik, M. 2007; Hirajima, T., Miki, et al. 2017). Copper and molybdenum sulphide ores usually have the similarly good nature floatability(Miki, H., Matsuoka, et al. 2017), meanwhile most molybdenum sulphide ore has tiny grained-size(Castro, S., & Laskowski, J. S. 2015.) and closed relationship with other sulphide and gangue minerals which result in the coper and molybdenum separation problem. Base on the nature of the ore and flotation properties of the individual minerals contained in the ore, there are two methods are usually used to deal with the copper – molybdenum ore, including bulk molybdenum/copper flotation followed by separation of copper and molybdenum minerals, sequential molybdenum/ copper flotation(Liu, G. Y., Lu, et al. 2012). The latter method has the shortcoming of hard to activate the depressed copper minerals in the previous molybdenum flotation process, which may result in a large loss of the copper from concentrate, this disadvantage would avoid while adopting the former method. bulk flotation followed by separation process is to get the copper-molybdenum concentrate from raw ore first then separate flotation the molybdenum and copper minerals, benefit from the excellent floatability of both molybdenum and copper minerals ( Malhotra, D., Rowe, R. M., & Bhasin, A. K. 1986; Cao, Z., Yue, et al. 2017 ), it really easy to obtain the mixed concentrate. In order to get the high quality copper and molybdenum concentrate, the key technologies and difficulties are to realize the separation of the copper and molybdenum minerals which have the very similar natural floatability (Raghavan, S., & Hsu, L. L. 2015; Nakhaei, F. 2014)."

Jan 1, 2018

By Yury V. Kulikov, Rakan Rahbani, Arkady Y. Senchenko

"The relevancy of complex minerals treatment is constantly increasing taking into account mineral resources depletion. Different refractory ores and concentrates, oxidized and polymetallic ores, as well as metallurgical products (slags) can be assigned to such mineral type. The treatment of such products via conventional flowsheets requires considerable capital and operational costs and does not always provide high recovery level of valuable components into a saleable product. Therefore, considerable amount of ores and metallurgical products are not treated, or treated inefficiently. One of the most promising approaches that allows economic treatment of refractory products is their ultrafine grinding down to 5-20 µm with subsequent processing or hydrometallurgy. Horizontal bead mills - the IsaMillTM, developed by Xstrata Technology, received their wide application in mining industry. Standard testing is performed under laboratory conditions in an M4 IsaMillTM (volume - 4 liters) to define the parameters of fine grinding. This mill completely simulates the operation of full scale industrial mills up to 50 m3 in volume (up to 8000 kW motor). The paper describes fine grinding technology performed in bead mills, and the importance of testing according to a certified method for industrial equipment selection. The paper contains description of promising directions of fine grinding technology application for several projects in Russia and Kazakhstan."

Jan 1, 2014

By R. Roufail

In this paper, the effect of different operating parameters of high speed stirred mill on the particle breakage mode is addressed. Morphological features of broken particles is investigated and related to the types of forces generated in the mill using Discrete Element Method (DEM). The stress intensities generated in the mill are varied by changing the agitator speed. The investigated agitator speeds were 1000, 1500, and 2000 revolution per minute (rpm). The minerals considered in this study are hard minerals (quartz) and soft, sulphide minerals (galena). The morphological features examined are roughness, roundness and elongation, which shed light on the mode of breakage during the grinding process. Particles that are rough, less round and elongated would imply that they broke via fracture, along their grain boundaries. On the other hand, the smooth, less elongated particles would mean breakage occurred across the grain, which is abrasion mod. DEM study complemented the understanding of particle breakage mechanism via tracking the types of forces applied on the particles. Normal forces imply compressive loading, which is presumed to impose fracture breakage along the grain boundaries, whereas tangential forces imply abrasion loading. Stirred mill grinding has been regarded as an attrition/abrasion process, whereas, this study showed that about 60% of total particles that are morphologically analyzed for both minerals were rough particles. Such an observation indicates that the fine product, which contain a significant amount of progeny from the coarse fractions are consistently broken via fracture. The morphology results agreed with the DEM findings, which indicated that the agitator speed, mineral type, and residence time would dictate the type and mode of particle breakage. Keywords: DEM, high speed stirred mill

Sep 1, 2012

By Sarra Scherbakova, Alexander Kurkov, Andrey Egorov

"Deep concentration of iron ores involves extraction, in addition to magnetite concentrate, of hematite and martite concentrates and recovery of other valuable components. A flotation technology was designed specifically for finely disseminated hematite ore, allowing producing saleable hematite concentrate containing 64-66% Fe. The main process challenge is caused by the presence of other ferruginous minerals such as carbonates, silicates, and phosphates, and fine hematite and martite mostly concentrated in the -0.044 mm fraction. Main operations of the processing circuit are removal of slime, flotation to remove impurities (carbonates, phosphates etc.) with an anionic phosphorous collector in an alkaline environment, hematite and martite flotation using same collector in a slightly acidic environment to produce commercial iron concentrate. Tailings of wet magnetic separation of magnetite containing 24.5% Fe and finely disseminated hematite ore containing 51% Fe were processed to produce iron concentrates with a yield of 15% and 50%, respectively, containing approximately 65% Fe and 5% of silica. Hematite flotation tailings had the highest content of gold (up to 0.09 - 0.11 g/t), while in other products it never exceeded 0.02 g/t. Using a Knelson concentrator was able to recover 40 to 45% of the gold into 3.31 g/t Au gravity concentrate. The success of gravity concentration is due to high gravitational contrast of gold to mostly quartz and aluminosilicates in the hematite flotation tailings. In general, the proposed process can be used as a solution to the challenge of selective concentration of finely disseminated iron minerals."

Jan 1, 2014

By R. Lestari

Newmont Batu Hijau operates with an accelerated mining rate to optimize life of mine (LOM) project economics. This results in a portion of ore mined being stockpiled for reclaim and processing throughout, and at the end of mine life. LOM economics can be further enhanced by preserving stockpiled ore value by mitigating oxidation effects. A detailed stockpile ore oxidation study was conducted to: ?? Develop a practical understanding of how oxidation affects ore value; ?? Determine how oxidation rate can be controlled, and; ?? Determine how oxidation effects can be mitigated to preserve ore value. The result of the study is a stockpile management strategy that significantly reduces oxidation related losses and, implementation of that strategy within practical constraints. Implementation includes installation of Controlled Potential Sulfidisation (CPS) flotation to facilitate oxidised sulfide copper recovery and, recovery of dissolved copper from stockpile drainage solution into saleable product. This paper describes the study results including managing and predicting stockpile oxidation with time, monitoring performance of implemented CPS flotation and recovery of dissolved copper from stockpile drainage. These are essential elements of successful long term mine operation in Batu Hijau.

Jan 1, 2014

By S. N. Sahu

Attempt was taken in this study to explore the misplacement phenomena in binary mixture in solid-liquid fluidisation system. The binary mixtures of hematite and quartz particles at different sizes were taken. The closed size range particles were taken to minimize the size and shape effect in fluidization. As both the minerals have appreciable density difference, the separation of both minerals with closed size range has an advantage. The experiments were conducted in different permutation and combination of different sizes of binary mixture to observe the fluidization phenomena. The samples were taken at different heights in fluidized zones and analyzed the distribution of particles of both minerals. The fluidization characteristics were evaluated with respect to operating and design parameters. It has been observed that when the terminal velocity of quartz and hematite particles is same or near to each other, then misplacement is significant. In general, the segregation index value is near to one, complete segregation takes place whereas this value is near to zero, complete mixing takes place. The experimental data were used to find out the segregation index for different size ratios of quartz and hematite particles and the values are within 0-1. When the size ratio is 1 or less, complete segregation takes place whereas this ratio is within 1.0-1.4, partial mixing takes place. Similarly, when the size ratio is within 1.4-2.0, complete mixing takes place whereas this ratio is within 2.0-4.6, then it moves towards complete segregation in inversion manner. Keywords: particulate fluidization, misplacement zone, bed expansion, terminal velocity, mixing characteristics, segregation index

Sep 1, 2012