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By J. K. Afidenyo

Microbial pretreatment of a double refractory gold ore was investigated using a white rot fungus, Coriolus versicolor (ATTC 20869) to improve gold extraction. A series of preliminary tests were conducted to determine the amenability of the ore to fungus degradation. Pulp density, temperature, pH and retention times were the process variables considered. Both a single. Stage and two-step processes were studied to establish process conditions. During the single stage process, the ore was contacted with the fungus culture (biotic) for 3weeks at 30°C and pH 10.0. For the two-step process, the first step involves ore contact with the culture medium (abiotic) at 45°C and pH 10.0 followed by fungal contact (biotic) at 30°C. Results indicated that carbonaceous matter is not degraded but passivated by the fungus; as preg-robbing activities dropped significantly from 18.1% to below 1.0%. The single stage process resulted in higher gold recovery than the two-step process Gold ex-traction by cyanidation of the pretreated ore was 78.9% for the single stage compared with 15.0% for the untreated ore. In the two-step process, only 73.3% gold extraction was achieved. Application of the two step process conditions to a high grade flotation concentrate, resulted in 93.3% gold ex-traction as against untreated concentrate of 30.5%. The results show that the microbial pretreatment process degraded sulfide sulfur, passivated carbonaceous matter and enhanced gold extraction from double refractory gold ore and concentrate.

Jan 1, 2014

By Willis Forsling, Prabhakar Swarna, Hanumantha Rao Kota

The solubility of wollastonite and its Hallimond flotation behavior as a function of dodecylamine concentration and pH are examined. The flotation response is characterized by adsorption and surface energy in the presence of amine. The methods of UV-Visible and FT-IR spectroscopy for adsorption and sessile-drop contact angle for surface energy estimation are employed. The results of wollastonite dissolution clearly showed its non uniform dissolution. The surfaces are depleted with calcium ions and became rich in silicon within 10 min of flotation time. Maximum flotation of wollastonite corresponds to a half monolayer coverage of amine, which is substantiated by the surface energy parameters. A good correlation between flotation, adsorption and surface energy as a function of amine concentration and pH was observed. The sudden increase in wollastonite flotation and amine adsorption at and above 5x10-5 M initial amine concentration is thought to be due to two-dimensional precipitation of amine on surface in accordance with the recent 2D-3D precipitation model of amine adsorption on silicate minerals.

Jan 1, 2003

By Ray Everson, Henry Kasaini

"We carried out adsorption experiments in chloride media to study the adsorption characteristics of Pd (II) anions on the surface of activated carbon. Throughout the experiments, we used commercial activated carbon pellets (0.8 Norit). The adsorption process was interpreted by using the ionisation and adsorption model. This implies that palladium anions were adsorbed physically on a protonated surface of activated carbon either as anionic complex species (PdCl4 -2) or aqua chloro-complex species [PdCl3(H2O)-] in acidic media. Furthermore, we established that adsorption of Pd (II) species was reversible at high chloride [Cl-1] concentration. The maximum adsorption capacity (Qsat) of Pd (II) anions averaged 27 mg/g. The Toth adsorption isotherms fairly predicted the equilibrium adsorption of Pd (II) species and the associated surface coverage.The effect of temperature and acid strength of the feed solution on the adsorption of Pd (II) ions were quantified. The adsorption kinetics was limited by external mass transfer since the effect of pore diffusion on the overall rate constant was negligibly small. A pseudo first-order kinetics model was used to describe the adsorption kinetics."

Jan 1, 2003

By Hong Zhong, Shuai Wang, Xin Ma

"In this paper, we report a simple and effective process for producing a surfactant mixture of O-isopropyl-N-ethyl thionocarbamate (IPETC) and 4-(tert-butyl)benzyl mercaptan (BBSH). The composite collector was synthesized via one-pot reaction of sodium isopropyl xanthate, 4-tert-butylbenzylchloride and ethylamine using tert-butyl alcohol as solvent. The whole process for the synthesis of composite collector involves neither foul smelling reagents or intermediates, nor any by-products requires special treatment for disposal, and thus can be scaled up to an industrial level. The flotation response of chalcopyrite and pyrite independently with IPETC and BBSH collectors and with their mixture (the mole ratio of IPETC and BBSH is 1:1) was assessed. The microflotation results showed that the collecting ability of BBSH was slightly stronger than that of IPETC and that IPETC was more selective collector than BBSH against pyrite, and that the composite collector displayed a stronger collecting ability toward chalcopyrite than IPETC, and superior selectivity for chalcopyrite against pyrite than BBSH. The batch flotation results showed that composite collector exhibited better performance than IPETC and BBSH. It was demonstrated that the mixing of IPETC and BBSH would give rise to a synergistic effect significantly enhancing overall flotation performance. In addition, the adsorption mechanism of BBSH on the surface of chalcopyrite was conducted by adsorption test and infrared spectrum measurement, and the results showed that the interaction of BBSH on the chalcopyrite surface was dominated by the chemical adsorption, and the formation of a strong S-M bond plays a key role in the adsorption of mercaptans on minerals surfaces. The developed flotation reagents with special preparation method is the author’s original design, patented (patent of the People’s Republic of China) and have no analogues in the world of mineral processing. (Application number 201810100107.1, ""Alkyl thioether alcohol compounds, methods for their preparation and applications thereof "", China).1. INTRODUCTION Froth flotation is an essential method widely used in the mineral processing industry to selectively separate valuable minerals from gangues[1]. Worldwide, more than 109 tons of materials are treated annually by this method with the majority being metal sulfides and oxides[2]. Nowadays, the judicious utilization of complex sulfides to meet the ever-growing demand of mineral resources gains more attention, due to the gradual depletion of deposits with high grade, making imperative the development of new high-efficiency collectors and mixtures of collectors to process complex minerals. In comparison to individual collectors, the use of mixtures has several notable benefits including lower dosage requirements, improved selectivity, rates and recovery and an increase in the recovery of coarse particles[3-9]. Moreover, in terms of cost and environmental issues, using collector mixtures can reduce the total amount of agents used, thus reducing the overall effect on the environment and economic costs without affecting the flotation performance. Therefore, the search for high-efficiency mixtures of collectors is still interesting and relevant."

Jan 1, 2018

By Dmitriy Makarov

The paper presents the modeling and analysis of oxidation of pyrite copper-zinc ore samples from the Letnee, Yaman-Kasy and Valentorskoye deposits. It is found, that the oxidized samples contain copper and zinc sulfates that are leached under the sample and water contact. It is shown, that sulfide floatability is decreased by the longer-term oxidation.We advise to improve nonferrous metals recovery by joint leaching and ultrasonic treatment of oxidized compounds. Study of the geotechnological processes of non-ferrous metal extraction, on the basis of two copper-zinc ore deposits shows, that heap leaching is of little use for the ores of the Letnee deposit. Leaching results for the Yaman-Kasy ore showed more promise.

Sep 1, 2012

By M. Z. He

Attractive particle interactions which underpin the sliming of gangue mineral particles onto valuable mineral phases are encountered in a number of flotation circuits. Sliming leads to poor flotation recovery of the valuable minerals and high recovery of the gangue particles in the concentrate. To mitigate sliming, low molecular weight poly-electrolytes are commonly used as dispersants during pulp conditioning prior to flotation separation of the valuable and gangue mineral phases. In the present work, the sliming mechanism of sericite onto chalcocite and the influence of interfacial chemistry and two anionic copolymer dispersants (carboxylate substituted polyacrylamide, polymer Cyquest 3223 and sulfonate substituted polymaleic acid, polymer P80) on the sliming interactions were probed in the pH range 5~9. It was shown that the sliming occurred under solution conditions where both chalcocite and sericite particles were negatively charged, as evidenced by their apparent particle zeta potentials. The suspension pH had a profound effect on sliming process as the extent was markedly greater at lower than higher pH. The sliming was found to be due to the chalcocite dissolution, Cu (I) release and oxidation to Cu (II), followed by hydrolysis and specific adsorption, leading to sericite particle surface charge reversal and the formation of electropositive sites on chalcocite surface in the pH range 5~9. Addition of polymer Cyquest 3223 or P80 not only increased the magnitude of zeta potentials of both sericite and chalcocite particles but also reduced the formation of Cu (II) ions and complexes, which mitigated the sliming behaviour. The adsorption of polymer Cyquest 3223 or P80 at 3 g polymer / kg solid or more had a significant impact on the zeta potentials of both sericite and chalcocite particles. Sericite-chalcocite particulate adsorption studies showed that sliming was completely suppressed via an electro-steric repulsion mechanism resulting from anionic polymeric dispersant adsorption at dosages > 3 g polymer / kg solid.

Jan 1, 2014

By Yuhua Wang, Huilan Yang, Yanqing Jiang, Dongfang Lu

"Generally, the concentration of bauxite flotation tailings is around 10%, a large amount of water in tailings needed to be recycled in the flotation process. Sedimentation and dewatering properties of tailings were investigated under different conditions. Surface high negative charges on mineral particles are the key factor to destroy the settlement of tailings when the pulp pH is around 8.9. Hence, the modification of pulp pH around 7 is necessary to the diminution of the repulsive force between mineral particles and then the acceleration of sedimentation of tailings. Anionic polyacrylamine with molecular weight of 14 million is the best flocculant for the settlement of tailings in all tested polyacrylamines. P-toluene sulfonic acid shows better properties than hydrochloric acid for pulp pH adjustment when anionic polyacrylamine with molecular weight of 14 million is used as flocculant. Although the flotation of diaspore is depressed in the presence of polyacrylamine using sodium oleate as collector, but the recycling water traded by the combination of ployacrylamine and p-touenesulfonic acid does not show the depression effects on the flotation of bauxite ore. The lower residual content of polyacrylamine in recycling water treated by the combination of ployacrylamine and p-touene sulfonic acid plays an important role. INTRODUCTION Generally, the waste water generated from mineral processing plant is usually treated by sedimentation, oxidization, electrodialysis, ions exchange, active carbon adsorption and flotation technology, and the treated water is also used again in the industrial process. Flotation was adopted widely to improve the quality of bauxite from low grade diasporic bauxite in China. For flotation, the grinding fineness of bauxite is over 90% -0.074 mm, sodium carbonate and sodium hexametaphosphate were used as regulators, so the tailings pulp is very difficult to settle and be dewatered (Y. Wang et al., 2004; Y. H. Wang et al., 2007; Wang Yu-hua et al., 2008; Wang Yuhua et al., 2011). The water recycling of bauxite tailings are becoming the highlight for the industrial application of the flotation process for bauxite ore. Researchers in China shift their attentions onto this topic."

Jan 1, 2018

By Paul W. Weiblen, Louis J. Cabri, Rolando Lastra

"Preliminary tests were done to determine whether comminution by electric-pulse disaggregation, or E-PD (cf. Rudashevsky et al; 1995), was more effective than using conventional crushing for Merensky Reef ore. A hand sample of the Merensky Reef was sawn in two: then one sub-sample was comminuted to .2 mm using E-PD at the University of Minnesota, and the other sub-sample was crushed to .2 mm using a conventional jaw crusher at CANMET.The products of the electric-pulse disaggregation and jaw crusher were fractionated by sieving and by a separation using a heavy liquid with a specific gravity of 3.3, because the proportion of platinum-group minerals (PGM) and sulphides to silicate minerals is very low. Thus, four mineral separates were produced: .2000 + 833 µm, -833 +208 µm, -208-µm float and -208-µm sink. All the mineral separates were studied by image analysis (Lastra et al; 1998). The main objective was to determine the liberation of gangue (silicate minerals), chromite, pyrrhotite, chalcopyrite, pentlandite and PGM. In the case of the PGM, a specific image analysis program was written to search and measure these minerals.The results show that the liberation obtained for gangue was similar (~99%) using either method of comminution. However, the liberation obtained for chromite (~89% vs. ~38%), pentlandite (~50% vs. 1%), pyrrhotite (~56% vs. ~38%), and PGM (~56% vs. ~1%) by E-PD was higher than that obtained by conventional jaw crusher, whereas the liberation obtained for chalcopyrite (~20% vs. ~71%) by E-PD was lower. Nevertheless, the image analysis of the products also showed that the PGM are strongly associated with pentlandite. Thus, for the Merensky Reef, liberation of pentlandite from the gangue minerals and chromite is important to recover more of the PGM. This maybe be significant because, in addition to increased recovery of platinum-group minerals (PGM), Merensky Reef pentlandite also contains significant quantities of valuable platinum-group elements like Pd and Rh (Cabri, 1981; Cabri 1988, Kinloch 1982, Peyerl 1983). Hence, the results indicate that for the Merensky Reef, electric-pulse disaggregation would represent a better comminution operation than a conventional jaw crusher would. In addition, the greatly improved liberation for chromite may find application for the PGM-rich UG2 chromitite."

Jan 1, 2003

Froth flotation is an industrial process commonly used for the separation of mineral particles. Bubbles sparged in a pulp collect and carry hydrophobic particles to the top layer of a flotation cell, the froth zone. There is a strong correlation between the stability of the froth phase and the flux of solids. However, flotation units placed in series operate, as a whole, in a non-steady state regime with the concentration of particle decreasing from one cell to the next resulting in a decrease in froth stability, which can compromise the recovery of valuables. Organic chemical reagents, frothers, are generally added to prevent fine bubbles from coalescing and to increase the stability of the froth phase. Frothers represent the second largest group of mining chemicals. It is crucial to understand the resulting properties of the frother on the froth phase in order to select the most suitable reagent for a particular operation. The bubble coalescence dynamic of three different surfactants, 1-pentanol, poly (propylene glycol), and tri (propylene glycol) methyl ether, were investigated in this study. In the first stage, the stabilisation mechanism of bubbles in a solution of surfactant was investigated using a specifically designed experimental setup. The coalescence behaviour of bubble pairs was recorded using high-speed video imaging in which information such as the coalescence time and the deformation of the resultant bubble upon coalescence could be extracted. The results were then compared between the different surfactants for several concentrations. It is shown in a study that the coalescence time increases with surfactant concentration until the Gibbs-Marangoni effect is suppressed by bulk diffusion. Conversely, the oscillation of the resultant bubble was found to be affected only at concentrations at which the film is saturated. The implications of the effects of surfactant type and concentration on the coalescence time and bubble oscillation in froth flotation are discussed. Keywords: froth flotation, frother, bubble coalescence

Sep 1, 2012

By P. V. Ramesh Babu

India has sizeable number of small deposits of rare metal bearing minerals namely columbite-tantalite, pyrochlore, beryl, lepidolite, spodumene and rare-earth element bearing minerals monazite and xenotime in different parts of India. Pegmatites, alkali granites, syenites, and the derived gravel and soils are the main source for rare metal and rare earth (RMRE) minerals. The RMRE minerals are classified as prescribed substances under Atomic Energy act of 1962 keeping in view the uses in the nuclear industry. Atomic Minerals Directorate for Exploration and Research (AMD) of Department of Atomic Energy (DAE) is the sole agency responsible for exploration and exploitation of RMRE minerals in India since 1962. The latest technological advancements and applications in the field of space, electronics, communication and nuclear industry using these metals and their products have necessitated to augment the production and resources of RMRE minerals. These minerals play a significant role in the technological and economic development of the country. The light rare earth element bearing mineral monazite is abundant in beach sands and is being commercially exploited by Indian Rare Earths Limited (IREL). Columbite-tantalite, the chief source for niobium and tantalum (Nb-Ta) metals present in the pegmatitic gravel are recovered by small mobile beneficiation plants. The cut and fill method of mining adapted is eco-friendly. The processing flow-sheet consists of wet sizing at ½ in and 1mm followed by gravity concentration of sized products utilizing the methods of jigging and wet tabling. The sizing equipment include revolving and vibratory screens and the gravity concentration equipments used are fixed sieve jigs and movable screen jigs for final upgradation. The gravity concentrates are further upgraded by magnetic separation to remove magnetite and ilmenite. The mine areas are reclaimed by filling with coarse size tailings and new plantations. These mobile pilot plants were earlier operated in Bihar mica belt, Jharkhand, pegmatitic areas of Karnataka and Nellore mica belt of Andhra Pradesh and are currently being operated in Bastar-Malkangiri pegmatite belt of Chhattisgarh and pegmatites of Jharsuguda district of Orissa. Beryl, lepidolite, spodumene and cassiterite minerals are the by-products from the pegmatite ores. Fergusonite, samarskite and microlite are the other niobium and tantalum bearing minerals which are also found in pegmatites. Xenotime, the chief mineral of yttirium generally occurs in granites and pegmatites. The rare earth minerals monazite and xenotime get concentrated in the placer sands of rivers and beaches. The occurrence of xenotime in the sands of Siri River and Deo River in Chhotanagpur granitic terrain in parts of Chhattisgarh and Jharkhand are an example. These sands containing 1-2.5% heavy minerals were processed by a mobile plant consisting of sizing equipments like trommel and vibratory screen followed by separation of heavy minerals from -1mm sands with the help of gravity concentration equipments like spirals/shaking tables/sluices. Xenotime and monazite from the pre-concentrate are further separated by magnetic and electro-static methods. The present paper illustrates the pilot plant set up for the recovery of rare metal as well as rare earth minerals. Keywords: small deposits, rare earths, rare metals, pegmatite, Nb-Ta, xenotime, India

Sep 1, 2012

By I. S. M. K. Ilankoon

In heap leaching the transport of the acid from the drippers to the surface of the ore particles is a major factor in the overall performance of a heap. This flow behavior is complex as the flow is unsaturated and occurs along a tortuous set of inter-particle channels and connections. Previous modeling of this system has used equations from oil and ground water flow to model these systems, but the applicability of these models with the larger particles found in typical heaps is suspect as these systems are not necessarily capillary dominated. In particular, as the characteristic particle size goes from below to above a few centimeters, the flow changes from capillary to gravity dominated. This means that typical heap leaching heaps cover this interesting, but complex, transitional fluid flow regime. In this paper a set of experimental studies of this flow, including PEPT (positron emission particle tracking) based tracer experiments, highly accurate liquid holdup measurements and axial dispersion experiments using salt tracers will be presented. In this study, flow through mono-dispersed particle beds was carried out. In particular, the hysteresis in the liquid holdup as the liquid flow rate into the particle bed is varied is investigated, since this hysteresis means that the relationship between flow rate and holdup is history dependent, an effect not included in models currently used to describe fluid flow in heaps. A theoretical model that describes this hysteresis will also be presented. Keywords: heap leaching, hydrometallurgy, modeling

Sep 1, 2012

By Sergio Castro, Janusz Laskowski

In the flotation in highly concentrated electrolyte solutions not only ionic strength but also chemical composition, flotation pH and mineral properties play an important role. As a result an improvement or depression may be observed. A strong improvement in the floatability of hydrophobic bituminous coals and other inherently hydrophobic minerals is characteristic for the "salt flotation process", which is carried out in concentrated electrolyte solutions at natural pH and without addition of any flotation reagents. However, pH is a key factor when saline and hipersaline waters with hydrolyzing metallic ions are used as process water. In the case of flotation of Cu-Mo sulfide ores in seawater, molybdenite is strongly depressed by the Mg2+ hydrolysis products when pH is raised to depress pyrite. Process water with a high content of Mg2+ and Ca2+ ions, and this also includes seawater, have deleterious effect on the anionic flotation of industrial minerals with fatty acids. The flotation of potash ores is carried out in NaCl-KCl saturated brine (6-7 mole/L of NaCl and KCl) with the use of long-chain amines. Such a high electrolyte concentration changes dramatically the amine Krafft point making the collector insoluble in brine; its mode of action entirely differs from that in conventional flotation processes.

Jan 1, 2014

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

"This paper is devoted to ultrafine grinding of processing products. This process allows one to include into operation complex ores which earlier were considered as inefficient and economically inadvisable to treat. Fine dissemination of valuable component often does not allow its liberation via standard grinding in ball mills, and therefore requires modern methods of ultrafine grinding (UFG). An example of successful ultrafine grinding usage is its application for crude flotation concentrates regrinding before cleaner flotation stages. A problem often arises with a commercial copper concentrate production in the course of copper ore flotation. Crude flotation concentrate regrinding in a ball mill does not provide for good liberation of the material before cleaner stages. UFG application allows one to get commercial copper concentrate with copper grade of 20% and higher. Another example of ultrafine grinding application is its usage for highly refractory pyrite product received after gold-lead scavenger flotation of polymetallic ore. Earlier this product treatment was economically inefficient. At current application of ultrafine grinding down to 85% minus 20 µm and subsequent gravity processing it is possible to pass major part of gold (73.4%) into concentrate. The constraining factor for UFG application in processing may be the chemical activation of minerals. In the result of this, flotation selectivity may decrease. Therefore ultrafine grinding application extends the areas of efficient usage of metallurgical processes. New technologies allow increasing the level of valuable metals recovery."

Jan 1, 2014

By Gabriel Barrios, Juan Pérez-Prim, Marcelo Tavares

"The application of High Pressure grinding Rolls (HPGR) has been growing in the mining industry for the last 10 to 15 years. The major benefits generally supporting this trend are better energy efficiency, improved grinding capacity, less sensitivity to ore grindability variations and higher metal recovery in downstream processes such as heap leaching and flotation. The HPGR machine comprises a pair of counter-rotating rolls mounted in a sturdy frame. One roll is fixed in the frame, while the other is allowed to float on rails and is positioned using pneumohydraulic springs. The feed material is introduced in the gap between the rolls and is crushed by the mechanism of interparticle breakage. Comminution performance is largely determined by the pressure exerted on the bed of particles by the floating roll hydraulic system. The operating bed pressure depends on the hydraulic system start-up parameters and the loading response of the feed material. The work describes how the coupling of the multi-body dynamic simulation with Discrete Element Method in which particle breakage is described using the particle replacement method, can be effectively used to predict the performance of the HPGR. The model considers important variables as the HPGR rolls geometry and design, the hydraulic spring system start-up parameters and the material loading response, to describe operational key outputs as material throughput, operating gap and roller pressure distribution. The preliminary version of the model has been used to predict the effect of material properties on the operating gap and the load distribution on the surface of the rolls, demonstrating that it can describe qualitatively the HPGR operation, indicating that the model will be a power full tool for the simulation and selection of industrial HPGR units."

Jan 1, 2014

By W. Fander, Zhonghan Zhang, T. Choo, J. Enraght-Moony

"This paper describes the mineralogical and metallurgical procedures used to determine the recovery and concentrate grade of heavy oxide minerals occurring in lode deposits. The data produced also provide vital information to the processing engineers, which allows them to develop the most suitable flow sheet for that particular heavy mineral, here called an Economic Oxide Mineral (EOM). It demonstrates how results are interpreted to ensure that the proper process is used at each treatment stage to optimise recovery and to produce the most suitable concentrate at that point. Reference is made to some of the current equipment and techniques that can be used to process EOMs. The paper shows that when assessing the economic potential of a new ore body, or existing ore treatment plant, ore characterisation (OC) is necessary. This is especially true for EOMs such as cassiterite (SnO2), wolframite ((Fe, Mn, WO4,) pyrochlore ((Na,Ca)2Nb2O6(OH,F)), and tantalite (MnTa2O6) where often what seem to be small changes in ore types can have major effects on recovery and concentrate grade. Due to advances in flotation technology scheelite (CaWO4) in some deposits can be less vulnerable to OC variability than other EOM’s. Thorough mineralogical examination is shown to be the fundamental basis of correctly undertaking OC. This is because mineralogical analysis identifies each of the steps required to ensure that all ore types and zones are recognised, and differences explained, and shows the benefit in using reference samples to compare differences in the ores. The OC methods used for EOMs containing metals such as tantalum, tin, tungsten and niobium are similar; if two or more of these EOMs occur in one deposit as separate minerals, then OC will show when and how these minerals should be separated. The OC techniques described for EOMs can also be tailored for other heavy minerals, precious metals and graphite."

Jan 1, 2014

By Jacques Eksteen, Sharif Jahanshahi, Neill J. Bartie, Shouyi Sun

The gradual increase in Cr2O3 levels of UG-2 ores has become a matter of concern for platinum producers in South Africa due to the formation of chromite spinels in melters. The effect of bulk FeOx/MgO ratio, Cr2O3, temperature and oxygen partial pressure on phase stability and composition in the system FeOx-MgO-SiO2-Cr2O3-Al2O3-CaO has been studied between 1400°C and 1600°C using the drop-quench technique. An increase in temperature was found to result in a decrease in [Fe/Cr]spinel. This effect is shown in Figure 1 for the six slag compositions investigated.

Jan 1, 2003

Goethite ore are the third most abundant source of iron. The overwhelming part of these ore is represented by low-grade varieties which cannot be used in iron and steel industry without preliminary beneficiation. Biomass is a renewable solid fuel, which is feasible for the substitution of coke and coal in the manufacturing due to its lower contents of harmful elements and abundant raw material sources. Utilization of biomass in iron ore sintering process as heating agent and reducing agent contributes to energy conservation and emission reduction. The biomass was mixed together with goethite ore for roasting process to investigate the effects of reduction roasting. The results show that the goethite ore is dramatically reduced and magnetized into maghemite by biomass with the biomass dosage less than 20% and the roasting temperature below 650 oC. When the goethite ore roasted with biomass, the magnetization values could be enhanced more than two orders of magnitude, meets the standard of magnetic separation, which could significantly reduce the iron beneficiation cost. Keywords: biomass, goethite, reduction, magnetization, roasting

Sep 1, 2012

By J. W. Ahn

Calcined calcium oxide from limestone is hydrated to manufacture calcium hydroxide, and then precipitated calcium carbonate is synthesized from calcium hydroxide. Precipitated calcium carbonate of various morphologies is obtained by controlled conditions of each step and characteristics of limestone, calcium oxide and calcium hydroxide. Especially characteristics of calcium hydroxide have the most influence on morphology of precipitated calcium carbonate character. In this study, therefore, it is investigated the specific surface area of calcium hydroxide and morphology of precipitated calcium carbonate according to hydration temperature. Calcium hydroxide hydrated at high initial temperature has larger particle size than that hydrated at low initial temperature. And formation yield of aragonite precipitated calcium carbonate has improved by using calcium hydroxide had larger particle size (hydrated at high initial temperature).

Jan 1, 2014

By V. F. Petrov, E. P. Olberg, S. V. Petrov

"The study was carried out using process solutions produced during cyanidation of gold-bearing concentrates from a gold-processing plant. It was found that the water contained a significant portion of thiocyanate (7910.0 mg/L), cyanide was virtually not present. The metals occurred primarily as iron (355.0 mg/L) in the form of ferrocyanide. Cyanide recovery was conducted using an ozone treatment process with reactors developed by the Environmental Department of Irgiredmet. The process design ensured complete utilization (100%) of O3, thus equipment operation safety increased.The recovery of free cyanide from thiocyanate was 76.6%, which corresponded to 5.12 kg of NaCN (100%) per 1 m3 of solution. Recovered NaCN can be used for recycling in hydrometallurgical processes.The operating costs estimation showed that the production cost of a tonne of recovered cyanide was US$1288.7, considering the prices of energy and commercial sodium cyanide in Russia in 2017, i.e. recovered cyanide is cheaper than commercial cyanide by 55.8%.INTRODUCTION Depletion of oxidized gold-bearing ores readily amenable to cyanidation has shifted focus to large-scale processing of primary ores with high sulphide content. Primary ores processing flow sheets involve gravitational and/or flotation concentration with subsequent treatment of produced gold-bearing concentrates. Typically, concentrates reporting to cyanidation contain considerable amounts of sulphur that can interact with CN- and further formation of SCN-. The use of refractory gold liberation methods (bacterial liberation, ultra-fine grinding) provides activation of this side reaction up to complete consumption of free cyanide in a short period. This makes water recycling unviable and impractical.The interaction of the sulphur content in concentrates and cyanide contributes substantially to consumption of NaCN required for efficient gold recovery. Inappropriate consumption of the main reagent achieves dozens of kilogram per tonne of material to cyanidation, and reaches approximately 100% when gold is recovered from activated sulphide-containing products (e.g. by ultra-fine grinding)."

Jan 1, 2018

By A. V. Golovanov, A. V. Mihailova

"NPO RIVS employs complex approach to engineering and design of the new facilities in close cooperation of Mining, Research, Hydrometallurgy, Design, Construction, Power Supply, Automation, Production and other departments. General Design Contractor (and then General Contractor) is directly involved in geological exploration, engineering surveys, floatability studies, feasibility study of process solutions and construction options. It delivers greenfield project and guarantee its efficient performance in future. Shiralgin is a small gold and copper deposit, gold average grade is 4.7 g/t. RIVS departments have studied ore floatability, developed process procedures for design and performed pilot testing. Construction of integrated plant including ore crushing and grinding, flotation and hydrometallurgy units with Dore gold production of 5 000 thousand tons ore per year (66.7 t/h) is recognized as economically viable. The technology used of separate dry stockpiling of flotation tailings and cyanidation tailings. Water circuit for concentration and hydrometallurgy is separated, too. Process design was performed based on BIM software like Autodesk Revit, Civil 3D, Rocscience slide using process procedures developed by RIVS Research units. Engineers provided modeling of primary crushing unit, coarse ore storage, main building (including grinding, flotation, thickening, filtration, loading, hydrometallurgy), tailings thickening unit, building for reagent storage and conditioning, tailings pond for dry stockpiling of flotation tailings and cyanidation tailings, sedimentation ponds, laboratories, infrastructure including Administration building and camp. Payback period is 3.5 years. 3D model of facility is currently stored at the State Agency of Geology and Mineral Resources affiliated to the Government of the Kyrgyz Republic.INTRODUCTION The Kyrgyz Republic has substantial potential of mineral resources including gold ores. Mining industry actively develops and involves international investors. Inventory includes 42 deposits (Figure 1) that have reserves of 616.4 t [1] of gold. The Kyrgyz Republic takes the third place in gold mining among CIS countries after Russia and Uzbekistan by producing up to 20 t annually."

Jan 1, 2018