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By Alim Gül, Güven Önal

"Recently, there have been some attemps on the treatment of low grade ores and old plant tailings due to the decrease in high grade ores and the increase in the metal consumption with increasing world population. Cost of mining and beneficiation of low grade ores become prohibitive since the costs of grinding before flotation make the process unfeasable. Therefore, preconcentration of these ores prior to flotation becomes more important. The concentration of ores preconcentrated in coarse sizes provides a decrease in investment costs as well as grinding and flotation costs. Additionally, the requirements of less space for tailing disposal and less reagent consumption are also important from the viewpoint of environmental considerations.In this study, ore sample containing 0.6 % Cu and taken from Küre-Asiköy ore body was used. Ores contained chalcopyrite and pyrite as main minerals and diabaz, quartz, chlorite and sericite as gang minerals.Samples were all crushed under 9 mm by considering the preliminary studies and float and sink experiments were carried out with the sample in the size range of –9+1 mm using different densities of heavy liquids. As a result of these tests, it was shown that 60 % of the material should be discarded as tailings with 0.1 % Cu content. By considering float and sink test results, the following experiments were performed by using heavy medium cyclone and jigs.As a result of heavy medium cyclone tests, which are conducted on the sample in size range of –9+1 mm, 57 % of the feed material was discarded as tailing with 0.08 % Cu content and 7 % Cu loss, while a concentrate containing 1.43 % Cu was produced with 93 % efficiency (Table 1). Jig tests were done with the samples in the size range. As a result of jig tests with –9+1 mm size group sample, approximately 46 % of feed material was discarded as tailings with 0.13 % Cu content and 10.6 % Cu loss, while a concentrate with 0.94 % Cu content was obtained (Table 2)."

Jan 1, 2003

By A. D. Shuloyakov, G. A. Finkelstein, V. I. Kurets, A. K. Vedin

"In disintegrating solid ores with mineral values disseminated in them, one of the principal tasks is to selectively separate valuable mineral particles from the matrix in which they reside, striving at the same time to keep their natural shape and size as intact as possible.The conventional mechanical disintegration methods do not meet this most important requirement in full. The other major objective here is to reduce electric power consumption during the fragmentation stage, since up to 65 per cent of the total power consumption at concentrators processing ores of non-ferrous, ferrous, rare, and precious metals is spent on disintegration steps.Numerous experiments conducted on dozens of ore types (tin, tungsten, and many others, as well as on rock containing diamonds, rubies, emeralds, etc.) have invariably demonstrated by far superior integrity of mineral values as compared with that obtained by mechanical as well as other types of disintegration.However, the process remains as power-intensive as ever which is due to the imperfect nature of the electro-technical devices that convert the network electric current into high-voltage electric impulses responsible for the disintegration process.The maximum capacity attained in disintegrating the hardest materials from 40 mm to 2 mm size in a single operating chamber with four high-voltage electrodes does not exceed 1.0-1.5 t/h. Attempts at increasing the number of electrodes and the capacity of the operating chamber have failed so far because of high overall dimensions and mass of the electrical part of the installation supplying the chamber with pulsating current, as well as of the commutation requirements. At the same time, a number of overseas operations have reported a significant breakthrough in their attempts to reduce dozens of times the overall dimensions and mass of the discharge impulse generating installation (EIS), which enables us to contemplate to increase the capacity of the EIS at least ten times in the nearest future. Yet, even with the currently achieved capacity of the EIS, these installations have found wide use in geological surveying, precious and semi-precious stones production, in grinding super hard materials, etc., since they provide spectacular selectivity of disintegration and thus the integrity of valuable mineral crystals."

Jan 1, 2003

By Barda K. Mishra, Surya P. Mehrotra

"INTRODUCTIONIn a jig, which is primarily a coarse mineral concentration device, the bed of mineral particles is pulsated with a stream of water resulting in the particles of different specific gravities. It operates in a cyclic manner – the jig cycle consists of four stages, namely, inlet, expansion, exhaust and compression. In the inlet stage the bed lifts up en masse. Near the end of the lift stroke the particles at the bottom of the bed start falling resulting in the loosing of the bed which, in turn, causes its expansion or dilation. During the third and fourth stages the particle resettle through the fluid, and the bed collapses back to its original volume. The pulsation and suction are repeated to bring about stratification with respect to specific gravity across the bed height. Various parameters affecting the stratification process include amplitude and frequency of pulsation, bed thickness, rate of hutch water flow, and feed characteristics. This paper first presents a review of various jigging theories and then describes a new approach to mathematical modeling of jigging employing the discrete element method.JIG MODEL BASED ON DISCRETE ELEMENT METHOD (DEM) APPROACHThe jig models based on DEM essentially involve tracking the position of each particle incrementally, applying Newton’s law of motion and a force displacement law at the contact. The model presented here is based on a three dimensional mathematical description of solid-solid and fluid-solid interactions. In this model, the force balance on a particle is extended to account for the effect of continuously varying fluid on the particle. The total force on each particle is made up of a known external body force, fluid particle interaction force and particle-particle and/or particle-wall interaction force. The fluid-particle interactive force is primarily made of drag and buoyancy. Di Felice’s correlation is used to evaluate the drag force. Solid-solid interaction is described by treating particles as discrete elements that are indestructible but interact with each other and any other elements present, such as walls, when they make physical contacts. A pair of spring and dashpot represents a contact The contact forces are computed from the amount and the rate of overlap of the particles at the contact. The motion of the particle is due to movement of the fluid, which transmits its energy through the particle-particle contacts. A computer program incorporating both the contact and the fluid model has been developed. It takes the operating parameters such as amplitude and frequency of the pulsating fluid, pertinent data concerning particle properties and the geometry of the jig bed as inputs."

Jan 1, 2003

By R. Peter King, Claudio L. Schneider, Reiner Neumann

Predicting the liberation spectra that is produced from breakage of two-phase ores under the random fracture assumption can be accomplished by measuring the conditional, on length, linear grade distribution directly from images obtained from a representative sample of the unbroken texture. The technique tremendously simplifies the prediction problem by avoiding the multiple convolutions that arise from the traditional method based on a description of texture from a measurement of the chord length distributions associated with each phase in the unbroken texture. For a 3-phase system, the phase transition probabilities associated with the textural information make the traditional calculation an almost insurmountable mathematical problem. The direct measurement procedure on the other hand can be expanded to three phases comparatively easily.

Jan 1, 2003

Mineral flotation is effective over a relatively narrow particle size range of approximately 10 µm to 150 µm. If the upper particle size limit can be increased, however, a run-of-mine ore may be coarse ground, and only the middlings are ground further to achieve required grades. This will result in significant energy savings and increased throughput. In this communication, methods of increasing the upper particle size limit will be discussed on the basis of a flotation model that can predict flotation from both hydrodynamic and surface chemical parameters. An example of increasing flotation recovery by control of a chemistry parameter is given.

Jan 1, 2014

By Zhang Yuejun, Feng Tianran, Shen Zhengchang, Han Dengfeng

"With continuous mining industry development and dressing plant scale expansion, flotation cell is developed towards to large scale and intelligence. Based on flotation cell scale-up theory and industrial practice, KYF-320 air-forced mechanical flotation cell with effective volume of 320m3 was successfully developed by Beijing General Research Institute of Mining and Metallurgy (BGRIMM) and adopted by China Gold Inner Mongolia Mining Co., Ltd, Luming project of China Railway Resource Group Co., Ltd, and Toromocho project of Chinalco in Peru. In this paper, the structure and technical characteristics of KYF-320 flotation cell are introduced, and the application of that equipment in China Gold Inner Mongolia Mining Co., LTD is demonstrated. The tank of KYF-320 flotation cell is cylinder-shaped, 8200mm in diameter and 7500mm high, with double froth lauders and large inclined angle cone bottom. 16 sets of KYF-320 flotation cells of which the processing capacity is 26,000,000 tons/a, are used in the second phase project of China Gold Inner Mongolia Mining Co., LTD. Their stable running shows the long life of impeller and stator and the power intensity (power consumption divided by effective volume of flotation cell) of KYF-320 flotation cell is only 0.73kW/m3 which is significantly less than that of small scale flotation cells. The industrial production obtains good results that the Cu grade of final concentrate of entire flotation circuit is 22.90% at the recovery of 86.73%, when Cu grade of feed is 0.35%, which indicates that KYF-320 flotation cell has good performance and can be widely used in large scale mine."

Jan 1, 2014

By Choi Sang-Ken, Chung Hun-Saeng, Kim Byoung-Gon, Park Chong-Lyuck

Fine grinding of crystalline graphite was conducted using a dry attrition mill with a vacuum system to investigate the characteristics of size reduction. Low pressure and high temperature conditions in the grinding mill were found to greatly improve the efficiency of the size reduction of graphite. Natural flaky graphite of .100 mesh was ground into sub-micron sizes, then over 90% of the product were able to be reduced below 1?without disrupting their crystallinity in a short period of time. Reducing the atmospheric pressure in the grinding environment promotes the removal of chemical species such as oxygen and water molecules adsorbed on the graphite particle, resulting in effective size reduction while maintaining the crystallinity of graphite.

Jan 1, 2003

By Ruiyang Zhang, Ping Fang, Dezhou Wei, Shuling Gao

A CFD based numerical simulation of flow characteristics of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The results show there exist several unsymmetrical envelopes of equal vertical velocities among both upward inner flows and downward outer flows in the hydrocyclone, and cone angle and apex diameter have remarkable influence on the vertical location of the cone bottom of the envelop of zero vertical velocity. It is also found that some tangential velocity isolines exist in the horizontal planes located in the effective separation region of hydrocyclone, and feed pressure has almost no effect on the distribution characteristics of both vertical velocity and tangential velocity of flow in hydrocyclone, however the magnitude and gradient of tangential velocity are made increased obviously, so as to make the high density particles motion velocity to the wall increased and to make the cyclonic separation effect improved. The simulation results also show when the apex diameter increased, the pressure of the fluid field decreased, however the pressure grads in the apex district increased, and the degree of changing is different as the cone angle, which showed some interactive influence of cone angle and apex diameter on the fluid field of hydrocyclone. While the feed pressure also has almost no effect on the pressure distribution characteristics, however the its magnitude and gradient are made increased accordingly, which can improve the separation accuracy according to particle density.

Jan 1, 2014

By Guanzhou Qui

The utilization status of copper ore resource, the application and development of biohydrometallurgy technology in the world was reviewed. Furthermore, according to the analysis of the characterization of Zambia?s copper resource, biohydrometallurgy technology was shown to be a good way to explore and utilize the enormous low grade copper resource, such as ore tailings and low grade copper ore in this country. Through the cooperation of CSU, China and MMMD, Zambia, ?CNMC-CSU Demonstration Base of Biohydrometallurgy Technology in Zambia? was launched and several biohydrometallurgy plants are being constructed, that indicates the biohdyrometallurgy technology would be applied soon in Zambia and even in the whole Africa. Biohydrometallurgy technology stands as an efficient alternative to the traditional pyrometallurgy process can be the key to unlock mineral resources value. Keywords: biohydrometallurgy, Zambia, copper processing, CNMC-CSU

Sep 1, 2012

By G. P. Wong

"The Inco Matte Separation process was the first commercial application using mineral processing techniques to separate nickel from copper from a slow-cooled matte in Sudbury since 1945. In Inco Sudbury operations, bulk sulphide concentrate containing chalcopyrite, pentlandite, pyrrhotite and some gangue minerals is flash smelted and converted to Bessemer matte. During the controlled slow-cooling of the Bessemer matte, discrete mineral grains of new mineral phases are formed: copper sulfide precipitates as chalcocite (Cu2S), nickel sulfide as heazlewoodite (Ni3S2) and a Cu-Ni-Fe alloy is also formed. Flotation is employed to separate Cc from Hz under high lime conditions (pH>12) with diphenyl guanidine (DPG) as both collector and frother.A simplified matte separation flowsheet is as follows. After grinding, the Cu-Ni-Fe alloy is removed by magnetic separation. All precious metals are recovered in the metallic alloy. Following the rougher flotation, a Cu concentrate is produced after cleaner and re-cleaner flotation in mechanical and column cells. Two Ni concentrates are produced: a high-grade Ni product containing less than 0.8% Cu from the scavenger column tails and a low-grade Ni product containing 5% Cu from the middlings circuit tails. A stream containing the inseparable Cc and Hz from the middlings circuit is generated and recycled back to the smelter. The quantity of this stream is typically about 3% of total feed and can be as high as 5%, greatly decreasing the overall matte separation efficiency. The large mass of the recycle stream is a direct result of poor Cc/Hz separation selectivity in the middlings circuit. The middlings circuit, consisting of a thickener, a regrind mill and two columns, processes two streams: cleaner tailings and scavenger concentrates. The thickener contributes significantly to oxidation due to the long residence time of the pulp in this unit."

Jan 1, 2003

By J. Gebhardt, D. McBride, M. Cross, S. Gilbert

Heap leaching of ores containing chalcopyrite offers a low cost option to treat low grade complex copper sulfide ore bodies. However, the slow leach kinetics of chalcopyrite at ambient conditions typically results in unacceptably low recoveries. As the mineralogy of new ore deposits becomes more complex and the effects of gangue chemistry exert a greater influence on copper sulfide leach behavior, the control of leach reaction chemistry becomes more critical. Computational fluid dynamics (CFD) technology has been useful in the capture of multi-phase interactions and provides a path to simulate complex fluid flow, gas and liquid phases, through the heap, along with species transport. Coupling the flow models with the reactive mineral dissolution, and the sometimes competing aqueous chemical and solid-liquid reactions, yields a comprehensive model of the heap leach process. The leach kinetics of chalcopyrite dissolution in heap conditions is examined, and the incorporation of chalcopyrite leach kinetics in the CFD model is described. The application of the model to investigate optimization of the heap is discussed.

Jan 1, 2014

By Rainer M. Lotzien, Michael J. G. Battersby, Jan Kleefeld, Julian V. Brown, Rainer M. Imhof

A new flotation system has been developed to improve the generally slow separating differentials of fine bubbles and fine particle suspensions. The new technology is based on established pneumatic flotation designs called Imhoflot which use intensive in-line pre-aeration to aerate the flotation pulp prior to its introduction to the separating cell. In the new system (see figure 1) this separation is speeded up dramatically by the introduction of centrifugal motivation in the separating vessel, without the use of internal moving parts. The design focuses on providing increased differential forces on buoyant mineralised bubbles and hydrophilic fines. The commercial benefit to industry is much reduced residence time, less than 30 seconds, which offers considerable cost savings in equipment and infrastructure.

Jan 1, 2003

By Masakazu Niinae, Kenji Aoki

"Electrokinetic soil remediation by electroosmosis and ionic migration is restricted to soluble substances. At a higher pH, the soil particles sorb more heavy metals than at a lower pH and the precipitation of heavy metals are promoted. Both mechanisms make heavy metals immobile, rendering cleanup more difficult and electrokinetic extraction inefficient.In this study, the effectiveness of introducing a complexing agent to enhance the removal of cadmium from kaolinite in the region of neutral pH by ionic migration is examined. The complexing agent selected was ethylenediaminetetraacetic acid (EDTA). The investigation was carried out in a laboratory-scale column containing kaolinite contaminated with cadmium. As the results of the study, cadmium migrates toward the anode without accumulation of cadmium and is successfully removed at the anode reservoir."

Jan 1, 2003

By Shenxu Bao, Ying Bian, Xiang Liu, Liuyi Ren, Yimin Zhang, Chun Liu

Efficient enrichment of high-carbon low-grade mica stone coal containing vanadium is a key problem in the mineral processing field, and the mature beneficiation process is yet to be developed and applied. In this paper, a special mineral mica type of stone coal containing vanadium from Tongshan, Hubei Province, China was selected as the research object. Chemical analysis results show that this mineral contains V2O5 0.71%, SiO2 49.28%, C 13.44%, and CaO 6.26%. Scanning electron microscope (SEM) shows that vanadium generally exists in all kinds of mica minerals in 20 µm to 50 µm fractions. Mica stone coal containing vanadium must be ground to a particular fineness (approximately 45 µm). To reduce acid consumption during vanadium extraction from stone coal through acid leaching, a pretreatment process was proposed to enrich micas by using shaking table and flotation methods. A new combined technology process was implemented, resulting in a 0.96% improvement in the vanadium grade of raw materials in the succeeding process. Vanadium losses were controlled to 4.57% through the pre-concentration process, which reduced the burden of the subsequent procedure. The content of high acid consuming minerals was also diminished, such that approximately 6612 CNY was saved from producing 1 t V2O5. Therefore, stone coal containing vanadium should be pre-concentrated by using an appropriate combined process to reduce costs.

Jan 1, 2014

By Georg Unland, Thomas Wegner

"Impact crushers are widely used in different industries to crush materials which can vary from soft to hard and from ductile to brittle. However, the sizing of impact crushers is still based rather on empirical than on scientific approaches. Therefore, a test rotor was developed in order to investigate the principles of comminution by impact. Rocks of diabase with different diameters were used to gain the crushing properties with the following results:RESISTANCE AGAINST CRUSHINGLikelihood of BreakageThe likelihood of breakage is a function of the impact velocity and the particle diameter. The likelihood increases with higher velocities and larger diameters. Maximum Crushing ForceThe crushing force is related to the area of projection of the rock. The smaller the particles and the higher the velocities the larger are the maximum related contact forces.Contact TimeThe contact time increases with the rock diameter whereas the influence of the impact velocity is neglectable.Mass Specific Crushing WorkThe mass specific crushing work decreases with the particle diameter and increases with the impact velocity."

Jan 1, 2003