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By Zhangm Zeqiang, Manman Lu, Hanquan Zhang, Hong Yu, Jintao Fu

"Pelletizing is an important technique in the ironmaking industry. Artificial and natural magnetites are materials that are widely utilized in the iron ore pelletizing process. In this work, the pelletizing characteristics of these two types of magnetite have been investigated in detail. The obtained results shown that in contrast to natural magnetite, the artificial magnetite concentrate exhibits stronger hydrophilicity, lower electronegativity, larger specific surface area, and rougher surface. In addition, the green pellets produced from the artificial magnetite concentrate are characterized by a higher compressive strength as compared to that of the pellets obtained from the natural magnetite concentrate. However, the shock temperature of the artificial magnetite pellets around 255 C is significantly lower than the threshold specified by the industry. The balling characteristics of the material obtained by mixing 20% of the artificial magnetite concentrate with 80% of the natural magnetite concentrate are considerably improved with respect to those of the individual components.INTRODUCTION Pelletization is an essential process of the ironmaking industry in China. Since the pellets produced from iron ore exhibit high mechanical strength, good particle granularity, and uniform shapes, pelletizing high-grade iron ores with good metallurgical reducibility can lower the coke ratio, improve their technico-economic index, and reduce the cost of processing pig iron in blast furnaces[1, 2]. Presently, high-grade magnetite is a material utilized for pelletizing various iron ores across the globe. However, its natural deposits have been depleting rapidly in recent years; as a result[3], China’s dependence on the foreign high-grade iron ores exceeded 70% in 2009 and reached the level of 87% in 2016. Hence, possible methods for the efficient cultivation of limonite, siderite, hematite, and other refractory minerals that correspond to low-grade, finely sized, inhomogeneous, and scattered iron ores have attracted significant attention [4, 5]. In particular, magnetization reduction roasting and magnetic separation techniques, which are widely utilized for obtaining high-grade artificial magnetite, represent effective ways of processing iron ores that can alleviate the scarcity of natural magnetite resources [6, 7]. The artificial magnetite produced by magnetization reduction roasting exhibits different characteristics as compared with those of natural magnetite (including the degree of hydrophilicity, surface potential, specific surface area, and other surface physicochemical properties[8-11], which significantly affect its pelletizing behavior. In this work, the surface characteristics of artificial and natural magnetites are investigated in detail, and their effect on their pelletizing properties (such as green ball strength, heat stability, and pelletization rate) are examined."

Jan 1, 2018

By G. Prabhulingaiah, D. M. R. Sekhar

"A phosphate deposit of estimated 6 billion tons of P2O5 is located 180 to 300 meters below the sea level, 185 kilometers north of port Luderitz, Namibia. The ore bed is 6 kilometers wide and 220 kilometers long. The ore deposit analyzing 16% P2O5 is loose sediment of 1.5 meters thick without over burden. Sizing of the ore to - 1.4 mm + 0.150 mm improves the grade to 23.54% P2O5 with a P2O5 recovery at 83.75% containing phosphate pellets and flakes of sea shells. Clay, bacterial debris as organic matter, flakes of broken sea shells and fine phosphate containing particles report to - 0.150 mm fraction and + 1.4 mm fraction contains sea shells and few phosphate containing pellets. The mineralogical composition of phosphate containing pellets is estimated (Droste, T.C., 2004) 80% frankolite, 6% pyrite, 4% illite, 3% quartz, 3% amorphous SiO2, 1% carbonates, 1% organic carbon and = 1% ilmenite, magnetite, zircon etc. The phosphate content in the pellets is around 27.7% P2O5. Trials to separate by gravity or flotation processes were not successful. Leaching of carbonates (sea shell flakes) under mild acidic condition (= 2% acetic acid or HCl solutions) or calcinations followed by leaching however yielded residues (concentrates) of grades 27.85 - 32.74% P2O5 at P2O5 recoveries ranging from 78.45 - 96.8% P2O5."

Jan 1, 2014

By S. Leroy

Grinding is the most energy consuming step in mineral processing, however, it is still poorly understood and its efficiency is difficult to monitor. Mill performances are traditionally measured at the mill discharge, on the basis of a mass percentage passing a certain sieve. This approach does not reflect what happens to the fines through milling. On another hand, if many macroscopic parameters, such as the percent solids of the pulp, its viscosity, or its mean residence time in the mill are known to be related to grinding efficiency, the link between these parameters and particle size distribution (PSD) is still unclear. Here, a methodology is established to understand the effect of ball mill operating conditions on particle size and shape distribution in the grinding process. The study focuses on the particular case of an Upper Group 2 (UG-2) platinum ore concentrator. Due to the very low grade of sulphide and PGM (Platinum group metals) in UG-2, grinding mechanisms are entirely control by gangue minerals. These two minerals have contrasted properties and PGM content and these properties immediately affect the entire recovery process. So, the grinding of both gangue minerals is studied on a size by size basis. At particle scale, three parameters are addressed: particle size, particle composition and particle shape. The specific behavior of chromite and silicate grains is demonstrated. As a conclusion, this study gives some clues to operate ball mills in a more efficient manner regarding chromite issue in the processing of UG-2. Keywords: ball milling control, UG-2, chromite, fine particle, particle shape, segregation

Sep 1, 2012

By Sergey Ulianov, Arkady Senchenko, Alexey Shvets, Arkady Bakotin

"This paper contains description of research results of technology development for copper recovery from weathered tails of iron processing plant. The predominant host mineral that contains valuable component is chalcopyrite occurring in its free form and in associations with ore and rock-forming minerals. Copper grade is 0.26-0.30%. Emulsion inclusions of chalcopyrite in pyrite and sphalerite were noted. Major problem is low copper recovery (30-35%) by flotation. When studying chalcopyrite in primary concentrate it was determined that the surfaces of many chalcopyrite grains are covered with oxide films which prevented collector attachment onto them. Second issue was deep association of chalcopyrite with pyrite and sphalerite. Sulfidizing reagent addition did not help to reach the required level of copper recovery to concentrate. In the result of research performed the technological flowsheet was developed including preliminary treatment of head material in a special unit aiming at oxide films removal, followed by copper rougher flotation on head size tails, crude concentrate regrinding and a number of cleaner flotation operations. After the treatment of weathered tails according to the flowsheet developed, copper recovery to flotation concentrate became 71.53%, at 23.46% copper grade. The suggested technology allows one to solve the issue with treatment of technology-related copper-containing stockpile material, as well as to include the ores where copper is represented by sulfide minerals covered with oxide films into processing."

Jan 1, 2014

By Yuexin Han

The wet preconcentration of haematite, comminuted by high-pressure grinding roller was studied, using the cylindrical ferromagnetic medium. The effects of various factors including rod diameter, rod gap and background magnetic field intensity (BMFI) on the performances of preconcentration for different size fractions and the force analysis of single mineral particles with different diameter in the separation zone were emphatically investigated. The results showed that as the rod diameter increased, the rod gap decreased, and the BMFI increased the tailings grade and the tailings yield reduced while the concentrates recovery raised that was regardless of variations in feed size distribution. For the -3.2+0.18mm size fraction preconcentration, the magnetic medium with a rod diameter of 4 mm and a rod gap of 7 mm at BMFI of 454kA/m is used to get a higher performance. For -0.18mm size fraction preconcentration, the magnetic medium with a rod diameter of 4 mm and a rod gap of 4 mm at BMFI of 263kA/m is used to get a higher performance. After the classifying preconcentration, at the optimum condition, the overall concentrate grade increases by 9.56 percentage points and the concentrate recovery is up to the 82.67% with a tailing grade of 10.68% and a tailing yield of 40.31%. The magnetic force, exerted on weekly magnetic minerals was proportional, to the specific susceptibility and square of BMFI. For the same BMFI, the magnetic capturing force on coarse particles increased, and that on fine particles decreased with the increasing of rod diameter. For the lean locked-particles, considering the gravity and viscous resistance of particles, rods with a big diameter were beneficial to the capture of coarse particles and had no influence on the capture of fine particles, while rods with a small diameter were good for the capture of fine particles and not suitable for the capture of coarse particles of lean locked-particles. Keywords: low grade haematite, high-pressure grinding roller, high intensity magnetic separation, pre-concentration

Sep 1, 2012

By Danfeng Xu

The majority of the world?s nickel (Ni) resources occur as laterite ores, which are exceptionally complex, lower grade (<1.5% Ni) and expensive to treat using conventional smelting and high temperature/pressure autoclave methods. Heap leaching is a promising, less costly, alternative technology for processing low grade nickel laterite ores. However, significant technical challenges remain with Nickel laterite heap leaching, preventing its general adoption. This paper presents some highlights of laboratory column leaching studies undertaken to characterise, evaluate and optimise sulphuric acid leaching behaviour of Nickel laterite agglomerates. They provide basic but valuable information regarding Nickel laterite agglomerate structure stability and leaching performance under industrially-relevant, continuous acid irrigation conditions. In particular, Nickel and other key metals? (e.g. Co, Fe, Al and Mn) extraction rates, free acid concentration, bed slump and structural changes were determined at a given acid percolation rate as a function of time. Potential implications of the findings, for devising strategies for improved Nickel laterite plant heap leach operations are discussed. Keywords: nickel laterite, column leaching, agglomerates, leaching kinetics, acid consumption

Sep 1, 2012

By Abhakumari

Effect of applied DC potentials on the bioleaching of a chalcopyrite concentrate in the presence of Acidithiobacillus ferrooxidans is discussed. Copper dissolution was the highest at an applied potential of +600mV (SCE), while all the dissolved copper got cathodically deposited at a negative potential of -600mV (SCE). Electrobioleaching at an applied potential of +600mV (SCE) was established at different pulp densities as a function of time. Effect of the magnitude of electrolytic currents on the activity and growth of bacterial cells was studied. Preadaptation of bacterial cells to the concentrate slurry and electrolytic growth conditions significantly enhanced copper dissolution. Electrochemical and biochemical mechanisms involved in electrobioleaching are illustrated with respect to oxidative dissolution and bio catalysis of anodic oxidation.

Sep 1, 2012

By Robin B. Batterham

"Since the 1970?s we have seen a marked corporate response in terms of the environment. In part this has come from regulation but it has largely come from stakeholders and the community. Rising expectations have in general been met. We now see a similar trend towards sustainability. At the same time, the importance of mining to the share market has decreased drastically and with that decrease has come the requirement for the mining sector to show returns similar in manner to other sectors. While rationalisation can achieve some progress towards these goals, the long-term requirement is for innovation, as it always has been. This paper looks to the logical goal of innovation within a sustainable mining framework and targets the removal of the desired metal values with minimal environmental footprint. It is suggested that broad ranging alliances will be necessary, particularly amongst the R&D suppliers, to achieve this goal. Industry will need to take an active role given the recent global restructuring.THE MARCH TO SUSTAINABILITYSince the 1970?s there has been an increasing corporate response on environmental matters. We have moved from matters environmental being issues relevant only to minority groups through a series of attitudinal changes by management. Whilst there have always been examples of excellent environmental performance, for many in the 70?s spending money on improving the environment beyond some minimal level was seen as a distraction from production or treated in a similar way to donations to the community. There is little of that attitude these days, as most mining companies have long since regarded the environment as a core business direction. Indeed, for some years one could note an escalation in matters of environmental reporting to the extent that the environmental performance of companies is now very public. In some cases, NGOs have even been invited to help certify and audit the reporting standards. Similarly with health & safety.There is now a rising expectation on the part of the community that social matters will also be given the same level of support as health, safety and the environment. This time around it would appear that the mining industry is at the leading edge of sustainability. The Global Mining Initiative (Global Mining, 2002) and the contributions to the Rio World Summit on Sustainable Development (Rio +10, 2002) suggest that sustainability is being taken very seriously by the mining industry. For sustainability it is convenient to use the Brundtland (1987) definition. This definition has widespread acceptance with governments, industry, environmental groups, financial institutions and individuals as a direction against which our activities and plans can be measured."

Jan 1, 2003

By S. M. H. Haddad, M. Saghaeian, R. Hejazi

"Due to limited water resources in mineral processing plants, increasing the efficiency of iron tailing dewatering system in order to obtain more usable water is very important. In this research, flocculation process, as one of the best method for water recovery, was investigated by using one organic cationic and three anionic types of flocculants with different dosages (10, 20, 30 g/ton) and iron ore tailing slurry (8 % w/w solidity) in series of graduated cylinders and obtained results were compared. it is observed that for tailing sample, the anionic flocculants have a significant effect on the settling rate of solid particles compared to the cationic types. Furthermore, effects of temperature (10, 23 and 43 ºC) and pH (2, 7 and 12) on the rate of settlement and turbidity was studied by utilizing the best flocculant. Findings showed that by increasing the amount of flocculant dosage, sedimentation rate went up and turbidity decreased. Comparison the out-put data of tests indicated that at temperature 23 °C and pH=7, the best results for both of faster settling rate and producing more clear water were reached. It should be considered that lower temperature has a more negative effect on the sedimentation rate and overflow water quality. So it will be predicted that for cold seasons, the consumption of the flocculant powder would be higher than the moderate or warm seasons. Also, coagulation/flocculation was evaluated by applying organic cationic coagulant added to anionic flocculant in three different times. Different ratios of coagulant to flocculant was examined (70%:30%, 50%:50%, 30%:70%) as well. Overall, utilizing coagulant had desirable influence on sedimentation experiments and obtaining high quality water. 1- INTRODUCTION In mineral Factories, among the important processes, solid-liquid separation process due to limited resources of water is very important and operates on iron ore tailing in settling tank as thickener in order to gain clear water for preventing water loss and applying again in plant units (Ciftci and Serhat Isik, 2017). Iron ore tailing include inharmonious compounds of iron oxides, silicates and aluminum-silicates. The percentage of solid in the tailing usually changes between 5 and 10 percent (Dash et al., 2011). One of the major problem about dewatering of tailing in thickener is solid-liquid separation of slurries with high stability because of fine particles. It means that rate of sedimentation is very slow and recovered water quality is inappropriate. This issue can be solved to a large extent by factors such as pH control, ionic strength and flocculation/coagulation process which results in aggregation of particles so that settlement by gravity is happened (Dash et al., 2011)."

Jan 1, 2018

By E. Burdukova

This paper explores the relationship between the rheological behaviour and mineralogical nature of three different natural ore types. Rheological measurements performed here on Platreef, Kimber-lite and Norseman-Wiluna ores are correlated with the variation of phylosilicate mineral content in these ores and the corresponding physical properties of selected phylosilicate mineral groups. Preliminary results show that the clay mineral group (talc) has the least effect on both Bingham yield stress and viscosity of the three ore slurries tested, whereas the serpentine mineral group has a dramatic increasing effect on the Bingham yield stress especially at very low solid volume fractions. The Bingham viscosity of the mineral slurry appears to be the most influenced by the presence of the swelling clay mineral group (smectite). Significant increases in either Bingham yield stress or viscosity due to elevated contents of these problematic phylosilicate mineral groups are likely to cause negative effects on the processing and manageability of mineral slurries but it is unclear which is likely to have a more detrimental effect.

Jan 1, 2014

By Avishan Atrafi, Marek Pawlik

"Gas dispersion properties of sodium salts of 6, 12 and 18-carbon fatty acids (hexanoic, lauric and oleic acid) were investigated as a function of pH. A strong effect of pH was observed on gas dispersion properties of fatty acids. At high pH for 12 and 18 carbon fatty acids, at which these surfactants formed a true solution, the gas dispersion properties were similar to those of MIBC. In the case of sodium hexanoate, which has a much higher solubility than the longer chain fatty acids and therefore does not form precipitates, the gas dispersion properties of this surfactant were strongly enhanced in the acidic pH range, where hexanoic acid was fully associated. This result is an indication that undissociated hexanoic acid is much more surface-active than anionic hexanoate. Only a small effect of the surfactant chain length on gas dispersion properties of the tested reagents was observed. The measured critical coalescence concentration (CCC95) values increase slightly by decreasing chain length and range from 5.8 x 10-5 mol/L (17.7 mg/L) for sodium oleate to 7.2 x 10-5 mol/L (16 mg/L) for sodium laurate at pH 10 and 1.9 x 10-4 mol/L (26 mg/L) for sodium hexanoate at pH 3.7. These are compared to CCC95 of MIBC, which is measured to be 8 x 10-5 mol/L (8 mg/L). The soluble molecular species were recognized as the most effective species in preventing bubble coalescence."

Jan 1, 2014

By S. K. Sharma, R. Markandeya, G. Venkateswara

"In this study, a three level Box- Behnken factorial design combined with Response surface methodology (RSM) for modeling of process parameters of Multi Gravity Separator (MGS) for recovery Iron values from sub grade iron ore, Deposit No. 5, Bailadila complex has been developed. The three significant operational parameters of MGS, Drum rotational speed (RPM), Drum inclination (degrees) and quantity of wash water (LPM) were considered in the experimental work. Other parameters like feed percent solids, shake frequency and shake amplitude were maintained constant. The ‘as received’ sub grade iron ore sample is admixture of lump and fines and chemically assayed 40.80% Fe, 40.90% SiO2, 0.24% Al2O3 and 0.22% Loss on Ignition (LOI). The obtained results were evaluated with the Box-Behnken factorial design, RSM and also Quadratic programming(QP). Second order response functions were produced for Fe in terms of grade (%) and recovery (%) of the concentrate fraction. Taking advantage of QP, it was observed that maximum grade of 62.21% Fe achieved at an inclination of 4.3degrees, 2.7LPM of wash water and at a drum speed of 198 RPM. Similarly a maximum Fe recovery of 65.37% weight can be achieved at 4.3degrees inclination, 2.6LPM wash water and at a rotational speed of 212 RPM Predicted values of responses obtained using model equations were in good agreement with the experimental values. The influence of the process variables of the multi gravity separator concentrator on grade and recovery of concentrate fraction were presented and discussed."

Jan 1, 2014

By R. K. Logric

Bor flotation tailings are very interesting from two reasons: first, is having due value presently, and second represent serious pollutant into this region of Balkan. This paper is only one small part of investigation about processing of valuable minerals from tailings, and desulphurization of this biggest pollutant in the same time, by refloating. The main objective of this work is to pay attention on this problem for resolve greatest environ-mental problem of Serbia and Balkan in the nearly future. Bor is potential regional risk spot, since that failure of its tailings dams would release high amounts of toxic materials that would reach the Danube River. The basic goal of this experimental investigation was finding some possibility for flotation tailings treatment by classical froth flotation. In order was obtained material effect through copper recovery, and environmental protection by moving the rest of reprocessing into the safe place. The work present obtained results of laboratory tests in two laboratories: laboratory of mineral and recycling technology at the faculty in Bor, and laboratory of department of mineral processing of ITNMS in Belgrade.

Jan 1, 2014

By A. A. Sirkeci

In the scope of this investigation comparison between impact breakage and compression breakage were carried out for the separation efficiency of minerals using a chromite ore sample. The ore sample was broken below 1 mm employing a laboratory type roll crusher and an impact crusher. Concentration tests were conducted on -1+0.5 mm, -0.5+0.2 mm and -0.2 mm size fractions using a Wilfley type shaking table. Test results showed a remarkable difference between two types of breakage. Both concentrate grade and recovery was in the favour of impact crushing. Furthermore, the shape of the broken particles also showed differences such that in the case of impact breakage they were more spherical compared to compressive crushing. The results of the shaking table con-centration tests showed that a concentrate assaying 48.4% Cr2O3 were obtained with 78.5% recovery in the case of impact breakage. On the other hand the concentrate grade and recovery values were 48.8% Cr2O3and 52.4% respectively in the case of compression crushing. The losses in the tailings were also in favour of impact breakage proving that differential breakage occurred between chromite and gangue minerals.

Jan 1, 2014

By K. Yoo

Cuprous oxide is one of the oldest antifouling agents and also acts as red pigment in these paints. In printed circuit board manufacturing industries, waste etchant contains a substantial amount of copper ion. In the present study, a process was suggested for recovering cuprous oxides from the waste etchant and optimum conditions were investigated to recover the cuprous oxides. The process consists of two steps: in first step, Cu powder is added into wastewater solution, and cupric ions re-duce into cuprous ions (Cu+Cu2+?2Cu+), where cuprous ions precipitate as cuprous chloride; In second step, cuprous oxide is synthesized by adding NaOH into cuprous chloride solution (2CuCl+2NaOH?Cu2O+NaCl+H2O). Optimum conditions were investigated to recover cuprous oxide in the processes. When copper powder was added into wastewater with copper ions, Cu concentration decreased from 15.6% to 2.6% and ORP decreased from 620 mV to -59.9 mV. This result shows that cupric ions reduced into cuprous ions. XRD data indicated that the precipitate was cuprous chloride powder. Using the cuprous chloride recovered and NaOH solution, cuprous oxide was synthesized. To investigate the optimum condition, various NaOH solutions were added into water with CuCl, and then pH, ORP, Cu concentration, Cu contents in precipitates were analysed. XRD data showed that main component of precipitates was cuprous oxide.

Jan 1, 2014

By R. Singh

The paper presents the results of characterization and beneficiation studies carried out on a lean grade tungsten ore sample from Degana, India. Basically, three different routes, involving gravity separation, magnetic separation, and froth flotation were studied for concentration of the sample by physical and physico-chemical methods. Considering the low recovery by physical methods, efforts were put in to produce a tungsten concentrate by physical methods suitable for subsequent hydrometallurgical recovery of tungsten as ammonium para-tungstate. This strategy proved quite helpful in minimizing the losses of tungsten in tailings. Based upon these studies a novel integrated technological process flow-sheet was developed for the exploitation of lean grade tungsten ore deposit of Degana, India. Keywords: lean tungsten ore, characterization, beneficiation, gravity and magnetic separation, hydrometallurgical extraction, integrated process route

Sep 1, 2012

By Hristo Stanchev, Veselin Mehandzhiyski, Sashka Kozhuharova, Stefan Stamenov, Alexandar Penchev, Nikolay Nestorov, Velika Stamatova, Ekaterina Todorova

"This article presents the results of comprehensive research on the quantitative distribution of gold content in the raw ore and tailings from the flotation enrichment process at the Ellatzite Med plant. The study is a quantitative and qualitative determination of the presence of gold in the ore processed by Ellatzite Med AD, as well as its behavior and distribution in the various metallurgical products of the flotation process. The representativeness of the samples taken is ensured by the frequency of sampling: four work shifts of sampling on different days within a period of four consecutive weeks. The form of gold present is determined both in the analyzed samples and in separate fractions - granulometric, magnetic, electromagnetic, heavy and light. A summarized diagram presents the phase distribution of gold in the final products of the dressing process. The results obtained are used for further analysis and evaluation of the actual technological parameters of the gold. It was established that an increase in the initial gold content, respectively in the content of native gold in the raw ore, with the current process, leads to an increase in gold losses, mostly in the native gold phase. The conducted analysis of the results from the comprehensive tests on determining the form of gold present in the various enrichment products gave rise to further research with the use of a Knelson centrifugal concentrator."

Jan 1, 2014

By A. N. Zagorodnyaya

The results of research on recovery of ammonium perrhenate from by-products of lead production are presented in the article. For the first time in the world, rhenium marketable products were produced on lead plant of Kazakhstan. Distribution of rhenium in lead production has been studied. During oxidative agglomeration of lead charge, 67.43% rhenium is sublimated and at that, 67.27% rhenium is trapped by the dusts of a system of gas purification, out of them 6.21% is transferred into different solutions, 1.89% into slime and only 0.09% into exhaust. During agglomerate smelting, up to 72% of its rhenium is sublimated and condensed in the dusts also. At leaching stage of sulphate product under dusts processing by the method of sulphatization, 15% of its content in the dusts is transferred into solution. The sorption method on the ionite ?N-21 has been proposed for recovery of rhenium from the solutions of sulphatization. At the same time, rhenium recovery from the dusts into commodity was 13%. The method of direct hydrometallurgy - leaching the dusts by solutions of sulphuric acid under presence of manganous concentrates, has been proposed as alternative method of recovery. This method has allowed increasing recovery of rhenium and other metals from the dusts into solution up to 90%~95%. Rhenium solvent extraction by ??? has been proposed for recovery of rhenium from the leaching solutions. At that, extraction of rhenium into marketable product from the dusts is above 75%.

Jan 1, 2014

By Jacek Kolacz

"Comex has carried out an extensive research work related to optimising sensor based sorting systems. The main target was to achieve efficient separation and maintain high capacity of the process. Eventually, the operating cost of the sorting process was investigated in terms of potential industrial applications and possible replacement of the existing traditional processing equipment. The study included an influence of the following factors on the separation efficiency: capacity, particle size and distribution, particle shape, material properties like colour, density and composition, as well as percentage of the rejected fraction. The above factors were also considered in the calculation models for the operating cost of the sorting process. In addition, other elements were considered like compressed air cost, cost of energy, labour cost, and necessary service and maintenance cost. All these elements were implemented into the calculation model allowing quick and effective evaluation of the major parameters for sorting applications. Finally, the study was carried out for two popular sorting principles: visible light sorting utilising differences in color, texture and shape and X-ray sorting using differences in density and chemical composition. GENERAL INFORMATION ABOUT SORTING POSSIBILITIES Application of the sensor based sorting systems, without any doubt, brings a lot of possible advantages in many mineral operations. The main advantage of the new system is related to its universality and at the same time very sophisticated image processing functions, which can be carried out in the same processing unit (Kolacz, 2014). Figure 1 shows the CXR-1000 system from Comex with 1 m belt width, in the configuration where many different analysed parameters can be used to provide particle separation. The image analysis system includes a camera installed either over the transport belt conveyor or at its discharge end. The system includes the X-ray attenuation analysis realized by the XRT system in the central part of the conveyor belt. The sorting system can be used with both optical and XRT analysis or separately depending on an application."

Jan 1, 2018

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

"The present paper contains study results of gold morphology and grain size distribution in flotation concentrates produced from original ore samples from deposits of different genesis. Pre-concentration methods were used with selective dissolution of rock minerals and mineral heavy medium separation to obtain statistically valid data on gold grain size and morphology in concentration products. Special attention is given to study of flash flotation concentrates that is mainly used for coarse gold, underextracted in gravity circuit. Analysis of geometrical optics has allowed to establish that during flash flotation gold grains more than 150 µm can be extracted from 10 to 35%, and in some cases single gold grains above 300 µm. INTRODUCTION Distinctive features of gold that have a significant impact, and in some cases, decisive influence on its recovery into saleable products are mineral shape, grain size and morphology of metal particles, paragenetic associations of gold. Peculiar feature of coarse gold is its easy extraction during grinding from associated mineral components like quartz, sulphide and other and almost complete recovery into gravity concentrates (Lodeischikov V.V., 1997). Morphology of native gold is so diverse that different gold grains are better extracted using different methods of concentration. Compacted and rounded particles are easily processed using gravity concentration but low cyanidable and hard to process using flotation. On the contrary, lamellar, flake, dendrite and capillary aggregates of high specific surface are easily cyanidable and under definite conditions it has strong floatability (Lodeischikov V.V., 1997). Flotation of gold-containing sulphide minerals and free gold takes place simultaneously during flotation concentration. In case of low-sulphide ores, native gold takes the basic load, having the high density (15.6 to 18.3 g/cm3, for pure gold – 19.3 g/cm3) it has limited size and morphology for successful flotation. It is known that flake gold and fine-grained gold up to 0.1 mm are easily extracted (Lodeischikov V.V., 1997). Authors of the present paper performed a study of gold granulometry and morphology in flotation concentrates produced from gold-containing ores from two deposits of different types: gold-copper oxidized hematite ores and low-sulphide gold-quartz ores. Ores are different by both host rock composition, mineralogical and petrographic features, gold grade in mineral assemblage and morphology and size of precious metal. Common for both ore types is low-sulphide content and presence of free gold."

Jan 1, 2018