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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

By Takashi Furuyama, Sukeyuki Mori, Takafumi Okuma, Norio Hashiguchi

The Tower mill KD-3 is an improved version of the laboratory mills VD-1, KD-1 and KD-2 in which the classifying column has been modified to ensure a quick discharge of products from the comminution section and, on the other hand, a better separation of coarse and fine particles; the latter being collected in a cyclone with a central spiral ribbon. To level the circling airflow through the classifying column and have a strict control over the maximum size of collected particles, a series of experiments was carried out, modifying the internal structure of the column: insertion of a vertical plate, a cone, or a horizontal net. The relationship established between the maximum size of products collected in the cyclone and the duct airflow rate indicates that, independently of the latter, the insertion of a cone in the classifying column could stabilize the maximum size of products collected in the cyclone around 15.1 - 17.5µm. With a horizontal net, the maximal size could be reduced to 8.4 - 11.3µm. This occurrence might result from the collision of coarse particles blown from the comminution zone with the base of the inserted materials and their settling down the bottom of the classifying column.

Jan 1, 2003

By R. Venugopal

The paper reviews the development of Mineral Engineering education and training programmes in India. It highlights the major academic programmes and describes the evolution of the curriculum and design of courses in response to the changing requirements of India?s mineral and coal industries. An outline of the efforts needed to sustain and further improve the existing programmes is also provided. Keywords: manpower, mineral engineering

Sep 1, 2012

By T. Saastamoinen, N. Heino

"The Olserum deposit located in Sweden hosts an indicated mineral resource of 4.5 million tonnes over 0.6 % TREO, exhibiting a relatively high proportion of HREE. Beneficiation of a composite drill core sample was studied in the flowsheet of magnetic separation of magnetite followed by REE minerals flotation. Primary testwork was performed to select an effective REE mineral collector and then the parameters of grinding size, collector and depressant dosages, slurry pH and density, conditioning time and temperature, and flotation time were tested for optimization of REE flotation. The studies of process mineralogy showed that the REE-bearing minerals monazite, xenotime and apatite were successfully enriched from the concentrations of 0.6%, 0.31% and 2.6% in the feed to those of 17.0%, 8.9% and 65.0% in the concentrate with the recoveries of 79.0%, 81.3% and 71.0%, respectively. INTRODUCTION The Olserum deposit located in Sweden comprises lower grade placer material with higher grade apatite-magnetite veins and hosts an indicated mineral resource of 4.5 million tonnes at 0.6% TREO, with 34% of that being HREO (EURARE, 2017). The mineralization was studied by Andersson et al. (2018). At early stage, high-temperature REE is characterized by abundant monazite-(Ce) and xenotime-(Y) coexisting with fluorapatite and subordinate amounts of (Y,REE,U,Fe)-(Nb,Ta) oxides. During a subsequent stage, allanite-(Ce) and ferriallanite-(Ce) formed locally, partly resulting from the breakdown of primary monazite-(Ce). Alteration of allanite-(Ce) or ferriallanite-(Ce) to bastnäsite-(Ce) and minor synchysite-(Ce) at lower temperatures represents the latest stage of REE mineral formation. The mineralogy and beneficiation were firstly studied by GTK Mintec in the EURARE project for a composite drill core sample. The Olserum is considerably smaller than the Norra Kärr deposit. However, REE are hosted by xenotime and monazite, both of which have well established processing pathways, and meanwhile, the Olserum has a high contribution of the high value critical REE (dysprosium (Dy), yttrium (Y), neodymium (Nd) and terbium (Tb)), which provide a unique advantage for its exploration (Tasman Metals Ltd., 2013). In this paper, flotation of the REE minerals in the Olserum ore was studied."

Jan 1, 2018

By M. Unesi, S. Haj Mohammadi, M. R. Abdoli, M. R. Garmsiri

"Hydrocyclone-thickener circuit is a promising solution to enhance the dewatering efficiency in mineral industries. The challenges in the circuit is reducing particle size in the thickener feed and the good feature is a rise in the retention time of sediments in the thickener. In this work, the effect of particle size, bed depth and residence time on the thickener performance were investigated. In this order, pilot scale columns were employed at Sarcheshmeh and Shahrebabak copper complexes. Furthermore, the influence of residence time was differentiated due to the variations in the bed depth and settling flux. Moreover, a new approach was introduced to estimate solids residence time in the thickener. results indicated that with smaller particles that are introduced to the column, the bed density as well as thickener discharge solids concentration dropped significantly. It was found that thickener discharge solids concentration fell from 59.6 to 33.8 % with reducing particle size from 130 to 22 µm in the settling flux of 20 t/m2/day. Additionally, it was found that longer residence time and deeper bed resulted in an increase in the thickener performance while the bed depth has a stronger effect. It was proved that employing a hydrocyclone prior to the thickener resuted in an increase in the dewatering efficiency.INTRODUCTION Thickeners are widely employed in mineral industries to recycle tailings and concentrate water content. A limited fraction of suspension water content is recycled using a thickener. For instance, about 50 percent of tailings water content could be recycled using a shallow bed thickener during copper processing. Since the scarcity of global water resources became more serious, the demand for improving dewatering efficiency in mineral industries became more significant [1]. A number of solutions were recommended to enhance dewatering efficiency of thickeners including optimization of current thickeners, employing deep bed thickeners and utilizing thickener-filter or hydrocyclone-thickener circuits. Optimization of existing thickeners is essential, however, it does not meet the significant demand for recycled water. The application of deep bed thickeners (known as paste thickeners) has been rising in the mineral industries [2] due to a higher dewatering efficiency while its costs is remarkable."

Jan 1, 2018

The relative abundance of coal in India compared to other fossil fuels makes it a natural choice as the primary source of fuel, be it for steel making, power generation or for other uses. The wide variations in nature and type of Indian coals formed during lower Gondawana period and categorized as difficult-to-wash due to its typical mineral matter association with the organic matrix call for suitable beneficiation techniques as the preferred option for quality upgradation. The good quality coking coals of the upper seams are fast depleting leaving behind the inferior quality lower seam coal. The lower seam coals presently being mined are mostly low volatile coking coal (LVC). They constitute about 50% of the total coking coal reserves in India. The beneficiation of Low Volatile Coking coals pose a major challenge and detailed R & D studies was taken up to study the beneficiation characteristics of these coals. The studies revealed that the liberation characteristics at coarser sizes are very poor and the coal is to be ground to finer sizes for liberation. The most important factor that determines coal cleaning efficiency is liberation of organic matter from mineral matter. To achieve liberation grinding is necessary as a result range amount of ultra fines (-0.063 mm) coal is generated. Presence of these large amount of ultrafine in the coal fines, often impose severe technical constraints affecting not only its floatability but also in the downstream treatment of the products like dewatering and cake formation particularly when it is beneficiating through froth flotation. In the present paper optimization of ultra fines (-0.063 mm) has been tried for a LVC coal of Jharia coal field for the better liberation and beneficiation of the above coal fines. It is observed that by optimized, combination of size and number of balls generation of fines can be controlled with liberation. Keywords: coking coal, liberation, floatability, dewatering

Sep 1, 2012

By Z. S. Abisheva

Rare and rare earth metals use quite often is an indicator of national economy development. The world structure of the rare-earth metals manufacturing countries in 2015 was presented as follows: China – 94.2%, India – 2.0%, Russia – 1.8%, the USA – 1.2%, Brazil – 0.5%, Malaysia – 0.3%. In Russia, large reserves of rare-earth metals, which reach nearly 28 million tons, are revealed. Kazakhstan, possessing a raw materials source of rare-earth metals, has all prerequisites for development of branch. Rare metals are manufactured in Kazakhstan incidentally by non-ferrous metals production. The production of indium, thallium, cadmium, selenium, tellurium, bismuth is made at the Ust-Kamenogorsk lead plant; tantalum, beryllium, niobium and molybdenum – at the enterprises of “National Atomic Company Kazatomprom” JSC. Production of a titanium, magnesium and vanadium is adjusted on “Ust-Kamenogorsk Titanium-magnesium Plant” JSC. Capacities for beryllic production yield are available on “Ulba Metallurgical Plant” JSC. The main producer of perrhenic production and osmium-187 is "Zhezkazganredmet" RSE. The single producer of gallium in Kazakhstan is “Aluminium of Kazakhstan” JSC; the capacity of enterprise is 25 t a year. In Kazakhstan innovative technologies for rare and rare earths mineral raw materials processing are created. The technology has been developed and a vacuum distillation apparatus has been created to purify crude selenium, which makes it possible to obtain a metal with a main component content of 99.9-99.99%. Technologies for processing of technogenic wastes and byproducts of the copper industry are developed. Implementation of technologies allow to obtain ammonium perrhenate, perrhenic acid, osmium isotope -187, tribasic lead sulphate, silver-concentrate. The technology of complex processing of black shales of Balasauskandyk deposit with the production of gold, vanadium, rare earth elements, uranium and ferrosilicon has been proposed. The processing was carried out using methods of autoclave leaching, sorption, extraction, precipitation. A highly profitable sorption technology for recovery of rhenium from solutions of underground leaching of uranium ores containing 0.2-0.4 mg/L of Re has been created. The organization of ammonium perrhenate production from solutions of uranium ore will significantly increase the volume of its production in Kazakhstan.

Jan 1, 2018

By Arkady Senchenko

At present, there are different traditional and modern methods for ore grindability evaluation. The correct and rational approach to sampling, testing methods and mill sizing enables one to design a workable technology. This paper contains TOMS institute experience in different grinding indices determination over the last 7 years (SAG Design Test, BWi, CWi, RWi, and other). Mill sizing examples and circuits modeling for the projects in Russia and Kazakhstan are considered. Keywords: ore grindability, SAG Design Test

Sep 1, 2012

By S. P. Nagaeva, O. U. Poperechnikova, A. V. Kuptcova

"In case of free gold presence in ore, there is always problem of a choice between the gravity-flotation and gravity separation flowsheets. Study of morphology of gold being extracted by different methods allows to find the most efficient solution. One of the latest methods of gold concentration for wide range of grain size (-0.8+0 mm) is a flash flotation. The paper presents comparative testing results of flash and centrifugal separation.The goal of the studies was to determine process and flotation parameters of flash flotation. In case valued minerals are soft if compared to host rock, such minerals tend to concentrate into circulating load of grinding circuit. Thus, valued minerals can be overground, and in turn, will result in low extraction in flotation circuit. Integration of flash flotation operation into process flowsheet has been evaluated. Flash flotation operation can be successfully used not only for gold but also copper, lead, nickel and silver minerals.With low-sulphide ores being a case study under laboratory conditions, various flotation (impeller rotational speed, air flowrate) and process (pulp density, collector consumption, frother consumption, time of flotation) parameters were studied in view of its impact on gold flash flotation. Experiments were carried out under laboratory conditions using special pneumatic mechanical flotation machines.INTRODUCTIONGravity separation is used for extraction of coarse gold before cyanidation and before flotation of polymetallic ores to increase gold total recovery into gravity copper and lead concentrates.Benefit of the flash flotation is efficient recovery of coarse gold carrier particles (sulphides) thus preventing its regrinding and, as a result, low recovery. Furthermore, combination of flash and conventional flotation results in final tailings that do not require further cyanidation.Combined gravity-flotation flowsheets are designed for concentration of ores containing gold within thewide range of grain sizes (see Table 1)."

Jan 1, 2018

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

By Dianyin Liang, Hongxiang Ran, Xiaoming Wang, Xiaoou Xia

"This paper presents a new magnetic separator, which can be applied to increase the grade of fine magnetite ore feeding of ball mill. This innovative equipment possesses a rotating magnetic system and has a magnetic field of rapid polarity change which can strengthen the destruction of magnetic agglomerations and the dispersion of minerals to improve the quality of separation. Now this type separators have been successfully applied in several large concentrating plants such as Shuichang Iron Mine under Shouang Mining Company in China. Finally, this paper outlines practical results focused on feed grade and tailing yield, the results are showing that the quality of feeding can be improve tremendously. Hence, a new generator of rotating magnetic field has been paved. INTRODUCTION Jidong region in China is the important origin of iron ore, the characteristics of the iron ore in this region is low grade and complex, the iron mine discharges fine powder tailings reaches tens of millions of tons each year, in the wind action easy to form sand, this poses a threat to the atmosphere environment of Beijing. In order to reduce the mixing of large amount of useless ore and reduce the energy consumption of mill operation, a high efficiency pregrinding equipment is needed. Rotating magnetic field separator (RMS) is an advanced equipment, the main advantage of RMS is the significant reduction in particle entrapment and can easily break magnetic agglomeration. This reduction is so significant that RMS is capable of operating very close to theoritical limit for separator precision and can increace efficiency in selection process.Some expenrimental work on dry rotating magnetic field separation has been carried out in July 1998 in the company Ka Pty Ltd, then in 2008 BGRIMM developed industrial separation XCTG0816 in Shandong province . The wet RMS was researched in1960s in Former Soviet Union and the first industrial equipment was developed by BGRIMM in 1970s,then in 1990s wet RMS was applied in Ansteel group corporation. In 2017,6 units large wet RMS (SXCT1230)which were the largest RMS was applied in Sichuan province. No matter wet RMS and dry RMS, although they are used in differenct applications, they have some common research.in addition ,they all have good use effect."

Jan 1, 2018

By Bisweswar Das, Barada Mishra, Hrushikesh Sahoo, Swagat Rath

Banded hematite jasper (BHJ) containing 45.2% Fe, 32.64% SiO2, 0.63 % Al2O3 and 1.25 % LOI is found difficult to beneficiate either by magnetic or flotation techniques due to fine intergrowth of jasper with hematite. Phase transformation by reduction roasting with activated charcoal followed by low intensity magnetic separation to achieve a suitable iron concentrate has been attempted in this study. The mineralogy of the ore and different roasted products has been studied by X-ray powder diffraction (XRD) and scanning electron microscope (SEM) to understand the reduction mechanism. The magnetite formation is observed at 850ºC while metallic iron appeared at a higher temperature. The effects of reduction variables such as reduction time (30-270 min), temperature (750-1050ºC), and reductant (1-12 %) using activated charcoal are studied. An iron concentrate with 64.65% Fe and 55.8% recovery could be obtained under optimum conditions of temperature: 850ºC, time: 1.5 h, and reductant: 6% by weight.

Jan 1, 2014

By X. H. Li, F. Xie, Q. Zhang, Z. H. Shen, S. Mao

"There is abundant rare-earth element(REE) in our country, but it is very fragmented in the earth's crust, and it is very difficult to mining or mining cost is extremely high. There are few of industrial value rare-earth deposits. There is a lot of concomitant rare-earth deposits, and the comprehensive utilization value is high. There is very rich carlin-type gold resource, associated with a certain amount of REE in the southwest of Guizhou province. In order toutilize comprehensively the resources, this paper conducts the study on the occurrence characteristics of REE in the ore. By the chemical analysis, the gold grade is 3.35g/t, the organic carbon 0.81%, the total REE 0.022%, which is a high carbon fine disseminated gold ore. By the optical microscope and XRD analysis, the major minerals are quartz, pyrite, calcite, limonite, arsenopyrite, mica, kaolinite, clay minerals, etc. In addition, there is a large amount of carbonaceous materials, such as organic carbon, graphite, which is harmful on leaching of gold. By the scanning electron microscopy analysis, there are thorium, lanthanum and neodymium, ytterbium, persimmon and other REE in the ore. Gravity separation shows that REE could be enriched to lighter material mainly, which indicates that REE disseminate closely with lighter materials.INTRODUCTION Carlin-type gold ore is important gold resource in the world, which are mainly distributed in Nevada and its vicinity, as well as the two Golden Triangle of Yunnan, Guizhou, Guangxi and Sichuan, Shanxi, Gansu province in China(Su W.C. et al.,2009; Xia G.X.,1996).Guizhou carlin-type gold ore is the second largest gold resource in the world(Muntean J L et al.,2011), distributing along the southwestern margin of the Yangtze plate, mainly mineralizing in the neopaleozoic-early mesozoic(Xie Z J et al.,2017). Many large gold deposits have been found in southwest in Guizhou in twentieth century, such as Zimuyou,Getang, Lannigou, Shuiyindong and Laowanchang gold deposit, and so on, and the gold reserves reach over 100 tons(Xia Y. et al.,2009).There is a certain amount of rare-earth resource in the carlin-type gold ore in the southwest in Guizhou province, and the current researches might mainly focus on characteristics of REE from the angle of geological mineralization(AnanyevY.,2015), not from the angle of separation and enrichment."

Jan 1, 2018

By H. R. Manouchehri

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

Jan 1, 2014

By A. P. Chaves, D. Jose Neto, M. G. Bergerman, E. S. Mano

"More complex ore comminution and concentration operations have found increasing application in the mining industry due to lower grades and higher complexity of the available ores. An alternative to coping with the higher capital and operating costs of ore processing plants is the use of pre-concentration stages. They allow removing a significant mass of material with little or no content of the relevant mineral before the ore is fed into the processing plant, with the consequent reduction in the mass to be processed in downstream operations. Significant benefits arise out of the use of pre-concentration, such as higher contained metal output without the need to increase the grinding or flotation capacity, and longer mine life. The grade of marginal ores could be enhanced to a level that would make their exploration economically feasible, which would result in increasing exploitable reserves. Nevertheless, few studies to date have assessed the resulting impacts on ore grinding energy consumption and wear after the gangue is removed through pre-concentration operations. This study evaluated the energy consumption and wear of grinding circuits in Brazilian mining operations in which the feed has gone through a pre-concentration stage. Such assessment was based on different samples of sulfide and oxide ores. Laboratory tests were carried out to investigate the power consumption and wear of grinding circuits with and without a pre-concentration stage. Laboratory test results were used to simulate industrial grinding circuits based on both alternatives and illustrate the environmental and economic benefits of each one.INTRODUCTION Increasingly complex ore concentration operations in several stages have found broadening application in recent years in view of lower grades and higher complexity of the available ores. An alternative to coping with the higher capital and operating costs of ore processing plants is the use of pre-concentration stages. Different ore processing technologies can be used for that purpose, such as magnetic separation, density segregation, and separation methods based on high-tech sensors (ore sorting). Currently, the most common methods are gravimetric processes, in view of their low cost, particularly jigging and dense medium separation methods, such as the drum and cone separators manufactured by Western Machinery Company, Teska, Drewboy, Norwalt, Dynawhirlpool and Tri-flo, and dense medium cyclones (CAMPOS; LUZ; BRAGA, 2010). The use of dry ore sorters has also grown significantly in recent years (Jose Neto et al. 2017). The selection of the separator type depends essentially on the ore particle size, required flows, and operating density ranges. All these methods may even be used after preferential blasting in mining (Grigg & Delemontex, 2015)."

Jan 1, 2018

By S. J. Neethling

"This paper examines the impact of several key variables on the performance of flotation cells. The study makes use of a simulator for the froth phase of the flotation vessel, as the main purpose of this study is to separate the impact of different variables from one another. In experiments it is very difficult to separate the effect of variables from one another as a change in a singe input parameter, such as air rate, invariably also affects many of the other key variables, such as bubble size and bubble bursting rates.In order to achieve this a base case simulation that is typical of many of the rougher cells found in sulphide flotation circuits was carried out. Four key variables, air rate, incoming bubble size, surface bubble size and the fraction of the bubbles flowing out of the cell unburst, were varied in order to obtain the system.s response.The most significant results were obtained when the bubble size was varied. An increase in the incoming bubble size has the effect of reducing the pulp zone recovery, but increases the froth zone recovery. If it were possible to vary the incoming bubble size without influencing the overflowing bubble size, the impact of the change would be unclear because of these two competing effects. The effect of a change in the overflowing bubble size has an opposite effect on the froth recovery, with larger bubbles resulting in lower froth recoveries.A final interesting result is that all the effects examined affect the process to a similar degree, which implies that none of these variables can be disregarded, either in industry or in further research."

Jan 1, 2003

By Yi Ran Zhang, Nawoong Yoon, Brent Hilscher, Maria Holuszko

"Ore sorting technology has been rapidly advancing in recent years. Improving expected mill feed grade has a significant benefit to project returns, and can no longer be ignored. When there is an increase in the mill feed grade while maintaining the same throughput, the mine will be able to process much more metal and improve the floatation recovery. There are many more factors that contribute toward the economics of the project by implementing sensor-based sorting technologies covered in this paper. This paper reviews the economic impact on an underground copper-silver deposit with references to the concept of ""profit recovery,"" which is the measurement of recovery based on rock profitability rather than just metal content. The economic impact of sensor-based sorting is discussed in detail throughout the paper. The preliminary economic evaluation of the project compares the mine's base case design versus a design incorporating sensor-based sorting. The paper's primary focus is on economic impacts rather than the explanation of the sensor based sorting results. The sorting data is presented on a scoping level and using a sensor-based sorting study where the best possible results are used for obtaining the grade recovery curves. Also, the breakdown and analysis of the project economics are based on the operating cost available from the particular operation. Any assumptions taken into consideration are also outlined and discussed. INTRODUCTION The mining industry has been adopting Sensor-based ore sorting technology fairly rapidly in the recent years. The ability to increase mill feed grade by rejecting waste grade rocks early in the processing stage is proving to be revolutionary for some operations. These potential outcomes should not be overlooked by both producing operations and prospective projects, thus leading to a wide range of studies on ore sorting. The answer to this is the creation of a new term and concept - Profit Recovery™."

Jan 1, 2018

By J. Menuge, G. Barker

"Liberation (QEM-SCAN) and surface chemical (time of flight secondary ion mass spectrometry -ToF-SIMS) analyses have been undertaken on plant Pb circuit flotation samples with the aim of defining the factors resulting in sub-optimal recovery. Lead flotation circuit feed, cleaner concentrate and tails samples were examined on a size-by-size basis using QEM-SCAN. Sulfide minerals accounted for approximately one third of the flotation feed with pyrite making up 16 wt.%, followed by sphalerite (13 wt.%) and galena (3 wt.%). Non-sulfide gangue minerals comprised calcium carbonates calcite (26 wt.%), dolomite (14 wt.%) with quartz, feldspars and barite all contributing > 5 wt.%. QEM-SCAN analysis indicated that liberation was not the primary cause of the poor flotation response. Principal component analysis was applied to the ToF-SIMS data derived from five samples (as for QEM-SCAN plus rougher concentrate and tails) to enable identification of correlated surface chemical components. Although a significant range of correlations were observed we focus here on those that show a discernible pattern throughout the float circuit. It was found that for the flotation feed the surface of galena were largely obscured but where Pb was observed there was a strong correlation to surface Fe. For the rougher and cleaner concentrates the galena surfaces were relatively clean with no correlation to Fe for the rougher concentrate and minor correlation in the cleaner concentrate. However, in the rougher and cleaner tails the clear correlation of galena with Fe was again apparent. These results suggest, in combination with prior studies of pyrite morphology, that the principal factor effecting grade is the rapid oxidation of the framboidal pyrite resulting in the contamination of the galena surface with a high loading of hydrophilic oxidised Fe species, thus depressing flotation."

Jan 1, 2014

According to the Darcy?s law, filtration rate should increase with increasing pressure drop (?P) across a filter cake. In centrifugal filtration, ?P is created by the free water present on the surface of a filter cake. Thus, ?P can become negative when the free water disappears from the cake surface, which makes it difficult to achieve low cake moistures. In the present work, we have developed methods of overcoming this problem by either increasing the air pressure inside or applying vacuum outside a centrifuge. Laboratory dewatering tests conducted using these provisions showed that the moistures of various minerals and coal fines can be reduced to the level that can obviate the need for thermal drying. The new concept has been successfully tested both at pilot- and full-scale, which lead to commercial deployment through Decanter Machine, Inc., under the trade name Centribaric® centrifuge. Keywords: dewatering, hyperbaric centrifuge, pressure drop, Darcy?s law, Centribaric® centrifuge

Sep 1, 2012

By S. K. Kawatra, T. C. Eisele

"Coal-fired electrical power generation plants produce 56% of all the electricity in the U.S., burning approximately 860 million tons of coal annually. This results in the production of 58 million tons of fly-ash; 19 million tons of bottom ash and boiler slag, and 23 million tons of desulfurization sludge.s annually. These are a considerable disposal problem, and it would therefore be very valuable to be able to sell these residues and by-products as useful materials, rather than paying to dispose of them in landfills. However, utilization rates are currently very low, below 32% even for the most thoroughly commercialized combustion byproduct (fly-ash). This poor utilization rate is a result of the high impurity content of combustion byproducts, which makes them unsuitable for existing markets.Mineral processing techniques are useful for upgrading and utilizing combustion by-products. Fly-ash can be processed to remove unburned carbon, or utilized as a binder component in ore pelletization and agglomeration processes; bottom ash can be processed to produce certain aggregate grades; CO2 emissions can be sequestered using modified leaching techniques; and many scrubber sludge’s require processing before they can be used for producing gypsum products.The experiments described in this paper were carried out to study the application of mineral processing techniques to upgrading combustion by-products, particularly flue-gas scrubber sludge. A process was developed for upgrading unoxidized Flue-Gas Desulfurization (FGD) sludge’s by removing the primary impurity (unreacted limestone). A combination of hydrocycloning followed by froth flotation reduced the limestone concentration to as little as 1.7%, while recovering 66% of the sludge weight as a clean product. The recovered limestone was sufficiently concentrated that it could be recycled to the scrubber for more complete utilization."

Jan 1, 2003