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By Y. Foucaud, C. Eswaraiah, L. Filippov

Enhanced gravity separators such as Falcon concentrator which uses additional centrifugal force, are the most common gravity concentration techniques used for fine particles processing. Hence, understanding the kinetics and separation mechanisms within these separators is of paramount interest. Recent research yielded a predictive physical model for the Falcon Ultra Fine (UF) which however does not explain some results obtained with industrial ores. This study aims to identify the mechanisms involved in Falcon UF separation with the objective of confirming or rejecting the hypotheses on which the current model is built and suggesting potential points of improvement. The Falcon UF kinetics is investigated through the processing of complex low-grade and fine-grained ores from the Altenberg tin deposit (Germany), the Tabuaço tungsten deposit (Portugal) as well as a synthetic iron ore. Saturation tests are performed on the Falcon UF by controlling the separation efficiency in terms of recovery and enrichment ratio with time or feed mass. Results show an evolution of Falcon UF performance with time in contradiction with the stationary separation hypothesis on which the physical model is based. Observation of the concentrate bed suggests the presence of erosion figures in furrows which may play locally an active role in the separation. In terms of Falcon UF separation timing, three phases can be distinguished. First, upon initial feeding of the bowl, a bed quickly grows unselectively and ultra-fine particles are ejected from the bowl until the bed reaches its final profile. Next, actual separation occurs with selective concentration of dense particles. Finally, capture sites saturate and recovery drops. The evolution of partition curves over time confirms the existence of two separation mechanisms. First, differential particles settling within the flowing film responsible for the ejection of small size particles during the whole separation cycle which is already accounted for in the physical model. The second mechanism involved may be explained by the action of lift force, neglected in the physical model, which acts preferentially on coarse particles deposited at the surface of the bed resulting in coarser particles being rejected in the tailings. Hence, the addition of a lift force component to the existing model is suggested to account for this second separation mechanism.

Jan 1, 2018

Micro-fine disseminated molybdenite was ground in a laboratory stirred mill using steel media and zirconium media respectively. The floatability of ground molybdenite and slurry chemistry was investigated. It was found that the total recovery of ground molybdenite using zirconium media was higher while the pH and Eh of the slurry are lower than that using steel media. When steel media was used, iron oxy-hydroxides had been generated coated on the surface of molybdenite, and decreased the floatability of molybdenite, especially of the -10µm particles. The iron and lead oxy-hydroxides was generated by the reaction between steel media with pyrite and galena associated with molybdenite. It was also found that changing the grinding media to inert can benefit the flotation of molybdenite. Keywords: stirred mill, grinding environment, floatability, micro-fine disseminated molybdenite, fine grinding

Sep 1, 2012

By M. R. Hosseini

Among all gravity concentration methods, Shaking-table is the most effective one from the metallurgical point of view. In this study, Shaking-table was used for concentrating a manganese ore sample from Ghasem Abad area in Kerman, Iran. Experiments were designed by using L8Taguchi design with five variables and each variable in two levels. The influence of each variable and their interactions on the operation of the device was studied. The variables under investigation were: table slope, table frequency, water flowrate, feed rate, and particle size. The manganese concentrate grade and recovery were used as response variables. It was shown that water flowrate, table slope, feed rate, and particle size are the significant variable on concentrate grade; while, all the variables influence manganese recovery.

Jan 1, 2014

Compressive crushing is applied in crushing plants used in mineral, mining, and aggregate in-dustry for fragmentation of rock materials. From a global perspective, the total volume of crushed rock is massive and corresponds to several billion tons. All societies have to fulfil a daily need of rock material products and its derivatives such as metals and minerals. The business for metals and minerals is global while the aggregates production is mainly a local industry. This paper presents a broader overview of optimisation with respect to product yield, use of natural resources and energy consumption. High level plant optimisation of compressive crushing plants is covered as well as real-time optimisation and optimisation of single production units. Each of three optimisation areas are presented and a discussion around how these three areas will be able to communicate with each other is given. Several models, e.g. process performance behav-iour with respect to wear, as well as fitness functions can be common for all three areas. Well-defined and representative fitness functions are of the utmost importance in order to assure that the optimisation results reflect the production targets. It is concluded that great benefits can be achieved by linking together different areas of optimisa-tion. The future for compressing crushing lies, without a doubt, in tailored processes both with re-spect to machines optimised for each customer, plant parameters and operation routines as well as an on-line adjustment, which takes into account current information and control possibilities.

Jan 1, 2014

By G. W. Zhang

Ultra-fine Stirred Mill is a kind of high energy efficient equipment for ultra-fine grinding, and has been the mainstream equipment in the submicron powder and slurry industry. This paper mainly describes flow-field numerical simulation of the three popular ultra-fine grinding mills: (respective-ly as) Disc Stirred Mill, Pin Stirred Mill and Spiral Stirred Mill, by means of the software Computational Fluid Dynamics (CFD). In the flow-field numerical simulation, the velocity gradient, shear rate dispersion of the flow-field, the viscosity dissipation rate were analyzed with CFD. It is discovered that Pin Stirred Mill has the highest velocity gradient in circular directions and the most homogeneous distribution of shear rate among the three. Flow-field numerical simulation provides a new way (and means to) for the parameter optimization design and project enlargement of Ultra-fine Stirred Mill. The experiments were also carried out, the results are consistent with the results of the simulation analysis. For example, in GCC grinding experiments under the same conditions, the specific energy consumption of Pin Stirred Mill with 3600L in volume is 15%~17% less, and its processing capability is 13%~15% better than Disc Stirred Mill. Now with its optimized structure and excellent performances, more than ten sets Pin Stirred Mill with 3600L in volume have been used in industrial production in Shandong, Guangdong and Hunan province.

Jan 1, 2014

By U. Ulusoy

Surface roughness and acuteness are known as the two of the main properties of the particle morphology affecting the behavior of the powders in the process. Since the techniques used for the morphological characterization of powders by 2-dimensional microscopic measurement from the polished sections that have some disadvantages, the 3-dimensional analysis has often relied on measurements of particle morphology. A review of literature data was presented for high-grade barite and pyrite particles ground by ball and autogenous mills to determine the morphological properties using a new 3-D approach based on BET nitrogen gas adsorption and Permaran methods. Micromeritics Flowsorb II 2300 instrument which employs BET nitrogen adsorption technique was used for the specific surface area measurements and the roughness of the particles. Permaran (manufactured by Outokumpu Oy) was used for the measurements of airflow resistance of powder samples for the acuteness. Spherical glass beads were used as reference sample for the acuteness measurements. The obtained parameters, which are surface roughness and acuteness, were corre-lated with the floatability performance of those mineral particles. The flotation performances of those particles ground in different mills (ball and autogenous) were also evaluated by a Hallimond tube. The results showed that lower roughness and acuteness values caused higher flotation recoveries for both barite and pyrite particles that were tested independently in different type of the mills. In other words; particles with smooth surfaces resulted in better floatability for barite and pyrite minerals studied.

Jan 1, 2014

By Z. He

Based on full investigation of the characteristic of sphalerite in the residue obtained from cyanidation leaching process and the study of the mechanism of the interaction between flotation reagents and sphalerite with the aid of electrochemical analysis, the reagent named YO was developed for eliminating the depression effect of CN- on sphalerite and reducing the dosage of CuSO4. The achievements have been used in commercial production for the treatment of the cyanidation residue to recover the zinc minerals, obtaining a zinc concentrate with grade of 56.49% Zn and recovery of 86.63% Zn.

Jan 1, 2014

By Xin Tan

In this paper, two types of low-grade complex zinc oxide ores (sandstone and limestone ores) from Yunnan province, China were investigated. A large number of argillaceous and alkaline gangue makes it infeasible to treat the ores with heap leaching. Although wet metallurgy can be considered, the lower efficiency of liquid-solid separation, the high cost, and low revenue limit this technology to be put into practice in large-scale. In order to solve this problem, a new technology combining mineral processing method with metallurgy technique is studied to process this refractory ore that consists of sandstone ore with 5.84 per centZn and limestone ore with 6.50 per centZn. The results of the tests showed that zinc can effectively be recovered from two types of the ores by using the new technology, and the acid consumption can be remarkably reduced. For sandstone sample, 82.96 per cent Zn was recovered by flotation and final Zn recovery by flotation+ hydro-metallurgy can be up to 78.17 per cent from the ore. In addition, for sandstone, acid consumption can be reduced from 270kg/t by direct acid, leaching to 76.92kg/t by flotation + hydrometallurgy combination. For limestone sample, 85.90 per centZn was recovered by flotation and totally 80.95 per cent Zn can be recovered by new technology which is a combination of mineral processing and metallurgy. Besides, H2SO4 consumption can be reduced from 450kg/t for sandstone originally to113.79kg/t after using new technology. One merit of this new process technology is that the zinc sulfides and oxides can be recovered without desliming in the flotation cells at the different stage and make sure the concentrate products as a good feed for hydrometallurgical technology. This study provided pretty good technical support for tapping low-grade refractory zinc oxide ores. Keywords: low-grade zinc oxide ores, limonite, non-desliming beneficiation, flotation + hydrometallurgy combination

Sep 1, 2012

By Z. G. Guan

The tungsten ore in Xingluokeng belongs to a symbiotic deposit containing granite and fine vein-type wolframite and scheelite. The tungsten (WO3wolframite) accounts for only 0.233% of the raw ore, 49.60% of the , 49.60% of the scheelite and 0.8% of the tungstite. The dissemination size of the tungsten ore is extremely uneven, with 0.02~1.28 mm for scheelite and 0.01~1.28 mm for wolframite. The dissemination size of scheelite is coarser than that of wolframite. The size of 83% of scheelite and 60% of wolframite is greater than 0.04 mm. The composition of minerals in the ore is quite complex. The major metallic minerals include wolframite, scheelite and pyrite, which are followed by molybdenite, chalcopyrite, arsenopyrite, limonite, magnetite, hematite and siderite. The major gangue minerals include quartz, feldspar, muscovite, biotite and sericite, which are followed by chlorite, fluorite, apatite, dolomite, etc. According to the dissemination features and liberation degree of the tungsten minerals, the technology flowsheet of gravity concentration for coarse particles and flotation for fine particles to re-cover the low-grade and fine vein-type tungsten minerals is adopted, and -0.7 mm is selected as the processing size. The closed-circuit grinding procedure, with the combination of the rod mill and high-frequency vibration screen, is adopted. The grinding product is classified into three products of -0.7 +0.2 mm, -0.2 +0.04 mm and -0.04 mm. The gravity separation is adopted for the former two to recover tungsten minerals and the flotation is adopted for the last one. Under the condition that the raw ore contains 0.23% WO3, some technology indexes of beneficiation have been achieved. The gravity tungsten concentrate contains 63.54% WO3 with the recovery 70.11%. The slime flotation tungsten concentrate contains 35.22% WO3 with the recovery 10.48%. The composite tungsten concentrate contains 57.53% WO3 with the recovery 80.59%. Thus, the tungsten minerals are re-covered effectively.

Jan 1, 2014

This investigation addressed two products from Samarco?s desliming circuit, namely underflow of cleaning cyclones and underflow of desliming cyclones. The roughing cyclones receive the product of the grinding circuit. The underflow of the roughing cyclones feeds the cleaning cyclones and the overflow feeds the desliming cyclones. The underflows of cleaning and roughing cyclones are combined to constitute the feed of the flotation circuit. These fractions were characterized and a new process route was proposed. The size distributions of the two fractions are quite different. The desliming cyclones underflow presents higher amount of material passing 37 µm and of ultrafines as compared with the cleaning cyclones underflow. Laboratory scale flotation tests were performed in a mechanical machine aiming at comparing the performances of these products in the presence of the reagents employed in the concentrator. Pi-lot scale column flotation yielded enhanced iron recoveries for both products in comparison with those achieved in laboratory mechanical cells, without impairing the concentrate quality. The in-crease in recovery was more significant in the case of the cleaning cyclones underflow. These results suggest the use of columns in the flotation of this product aiming at increasing the overall iron recovery. Nevertheless the results also showed that the use of columns to float the cleaning cyclones underflow should also be taken into consideration. Despite the fact that this product requires a longer residence time in order that the required silica content in the concentrate is achieved, the indication is that higher levels of iron recoveries might be reached. The conclusion is that, due to the different behaviors of the two products, they should be processed in distinct circuits to maximize the iron recovery.

Jan 1, 2014

By Q. Cui, Z. G. Song, S. S. Lin, S. Q. Li, S. S. Lu, G. B. Zheng, A. J. Ren

"Mine tailings is one of the most important bulk industrial solid wastes, but its rate of comprehensive utilization is relatively low. Efficient separation, recovery and utilization of the valuable components is one focus of the comprehensive utilization of tailings. Beneficiation recovery of the valuable minerals is the most direct comprehensive utilization method for tailings. There are generally different kinds of nonmetallic minerals contained in the nonferrous metal mine tailings, which are secondary mineral resources waiting for further developing and recovery. Comprehensive utilization test studies on fluorite in tungsten beneficiation tailings and feldspar in molybdenum beneficiation tailings have been carried out by author and good test results are achieved. Some of the technologies developed in the test study have been applied in industrial productions, which have been working well. The economic, social and environmental benefits are remarkable. Our test studies and some production practices will be summarized and current situation and existing problems of comprehensive utilization for nonferrous metal mine tailings will also be discussed. Assumption and prospect for the future study on comprehensive utilization of nonferrous metal mine tailings will be brought at last.INTRODUCTION Mine tailings is one of the most important bulk industrial solid wastes, but its rate of comprehensive utilization is relatively low. Efficient separation, recovery and utilization of the valuable components is one focus of the comprehensive utilization of tailings. Beneficiation recovery of the valuable minerals is the most direct comprehensive utilization method for tailings. There are generally different kinds of nonmetallic minerals contained in the nonferrous metal mine tailings, which are secondary mineral resources waiting for further developing and recovery. Comprehensive utilization of nonmetallic minerals of nonferrous metal mine tailings not only can improve the value of the ore but also reduce the stock of tailings, being the key to reduce emissions at source for exploitation of nonferrous mineral resources (Cai, Yang, 2000)."

Jan 1, 2018

In order to determine the optimal process parameters of agitation leaching and provide industrial process design parameters, experiments were carried out on leaching behaviors of copper oxide ore with high mud content. Condition tests show that the main factors affect the leaching efficiency as follows: Temperature, Initial acid concentration, leaching time and particle size. As the temperature increases, the copper leaching rate was increased. At 60 ?, the initial acid concentration 80g / L, leaching time 2h, liquid-solid ratio 2:1 and grinding fineness65%-0.074mm, the optimal copper extraction was 83.15%, the acid consumption was 187.91kg / t. ore. Keywords: agitation leaching, copper oxide ore, mud

Sep 1, 2012

By B. Rai

Aluminum is produced by the Hall-Héroult process, which involves passing a current through a molten mixture of alumina dissolved in cryolite (Na3AlF6) to reduce the alumina to aluminum. This process occurs in an electrolytic cell comprising a steel shell lined with a carbon cathode and refractory bricks. After a certain period of operation, the carbon cathode deteriorates and is removed from the cell along with the refractory bricks. These removed materials are referred to as spent pot lining or ?SPL?. Typically, 30 Kg of SPL waste is generated for every ton of Aluminum produced. Globally aluminum smelters produce more than 500,000 tons of SPL each year. Even though SPL has a high fuel value (8000 to 9000 BTU/lb) and contains valuable metals, it is classified as a hazardous material due to its cyanide content and leachable fluorides. Various disposal/recycle techniques have been developed over the years for SPL but none of them is satisfactory. Thus, large quantities of SPL are still being dumped in landfills. In some countries, even the land filling of SPL is not permitted. The safe disposal of SPL thus remains a challenging problem to the aluminum industry and the search continues to find methods of converting SPL into a non-hazardous waste and/or recovering the valuable materials contained in the SPL. We have developed a process to produce hydraulic setting cements (eco-cement) containing a novel fluoride rich cementitious phase, from SPL by an energy efficient, low temperature clinkering route. A raw mix blend of SPL, lime/limestone, calcium sulfate and tailings sands based on a set of design criteria developed by us, is clinkered in a two stage process; 2 hours soak at 800 °C followed by clinkering at 1000 °C for another 2 hours, to produce a soft clinker. The SPL eco-cement is made by grinding the clinker to a fineness of 5000 cm2/g Blaine with 1% by weight borax as a set retarder. A good quality cement having as high as 20 % by weight of SPL in the raw mix (28 % by weight in the cement clinker) is thus produced. The physical properties of the SPL cements are found to be comparable to the Indian standard (IS) specifications for Ordinary Portland Cements (OPC). We have produced the cement in a few Kg batches and tested the reproducibility of results from batch to batch for further scale up. Once commercialized, this process has a potential of converting SPL into value-added cement products. Keywords: cement, spent pot lining, clinkering, fluoride, aluminum, ordinary portland cements

Sep 1, 2012

By F. M. Zafar Kaifi

Magnesite producing companies rely on high grade purity MgO. The mineralogy of magnesite has a significant impact on the manufacturing of magnesite bricks. The manufacturing process of bricks companies utilizes 90% magnesite from 85%~90% MgO. The main objective of the magnesite bricks was to utilizes the indigenous raw material available in bulk quantity. With better under-standing of chemistry of the mineral species and strict control of bricks manufacturing/processing conditions can be better produce efficiently, a low cost high quality bricks with minimum detrimental environmental impact.

Jan 1, 2014

Poor floatability of fine particles is known to be the main cause of the low recovery of ilmenite in Panzhihua, which is the largest titanium mine of China. To get an optimum ilmenite recovery, selective flocculation, and flotation of fine ilmenite was investigated through flotation tests, particle size analysis, zeta potential tests and scanning electron microscopy. The results indicate that carboxymethyl cellulose (CMC) shows flocculation effect for both ilmenite and titanaugite without selectivity, while selective flocculation could be realized by the combination of water glass and CMC. It is because that competitive adsorption would take place on these two kinds of mineral when water glass and CMC are used together. On the surface of ilmenite, the adsorption ability of CMC is stronger than that of water glass, so that CMC can absorb to the same extent irrespective of the presence of a pre-adsorbed layer of water glass and ilmenite particles is flocculated by CMC. The same cannot be said of the titanaugite phase as water glass strongly adsorbs onto the titanaugite, and the adsorption of CMC is hindered. Therefore, the titanaugite particles keep dispersion. Furthermore, the flotation of fine ilmenite particles is feasible as the ilmenite floccules could react with sodium oleate. In the flotation separation of Panzhihua ilmenite ore, the recovery of TiO2 increased from 52.63% to 68.28% by selective flotation. Keywords: ilmenite, flotation, selective flocculation, adsorption

Sep 1, 2012

Hydrofluoric acid (HF) is traditionally used in plant operation to separate feldspars from quartz. It acts during the conditioning step as a pH regulator and an activating agent providing an excellent selectivity. However, a corrosive chemical environment and the ecological impacts from the potential fluoride ion contamination are limiting factors to use this chemical agent at an industrial scale. Investigations of the amine-feldspar interactions in the absence and presence of non-linear long-chain alcohols were carried out on two ore samples. The presence of alcohol molecules led to form a closed packed layer only on the surface of feldspars. The highest order and packing at the feldspar surface were observed with a particular alkyl chain structure as Guerbert alcohols. A new flotation process was developed and tested at both lab and pilot scales on different feldspar ores. The Guerbert alcohols allow to perform a feldspar concentrate with very low content in quartz (2.3-3.5 %) and feldspars recovery from 78 to 81 % while the aliphatic isoalcohols show a more higher recovery level (88-89 %). New HF-free process is strongly dependent on the pH range (1.7-2.5) and sulphuric acid consumption during conditioning steps. Optimal amine/alcohol weight ratio is ranged between 0.8 and 1.0. The values below 0.8 decrease strongly the flotation selectivity and the quartz recovery within the feldspar concentrates is higher than that occurs with HF.

Sep 1, 2012

By Jun Xiao, Jianwen Yang, Yanhong Dong, Daixiong Chen

"MANGOTE Surface oxidizied mine is a gold-bearing deposit in Congo's Mai-Ndombe Province. In the past decades, the ore has been exploited in a crude way by local farmers, which directly causes the severe processing difficulty and lack of economy of cyanide leaching. Hunan Research Institute for Non-ferrous metals (HRIM) is currently investigating options to recover gold through understanding the mineralogical characteristics of MANGOTE surface oxidized ore. Chemical analysis , X-ray diffraction(XRD) and Quantitative Evaluation of Minerals by SCANing electron microscopy (QEMSCAN ) were conducted on samples from mine site. The bulk analysis results showed that gold separation of gold from gangue minerals was feasible after grinding the ore samples to 86.53% -74µm and adjusting the pulp specific weight at 100g/L, and gravity separation was conducted with using spiral chute after grading of fine particles. The research results highlight relationship between mineralogical characteristics of abandoned ore and economy of comprehensive utilization that might be directive experience to similar cases. INTRODUCTION The occurrence state of gold in natural gold minerals determines the basic recovery and recovery effect of gold(Komnitsas, C., & Pooley, F. D. 1989). The occurrence of gold in the ore refers to the form of gold in the ore.Generally the existing state of gold can be divided into four major categories according to the viewpoint of the dispersion system: independent minerals and gold, a coarse dispersed system;colloidal gold, a colloidal dispersion; solid solution gold, is atomic ion dispersion; adsorptive gold, according to the adsorbed particle is the micelle or ion, respectively is a colloidal dispersion or ion dispersion(Mao, S. D., & Yang, R. S. 2009; Liu, J. J. et al. 2007; Horisberger, M., & Rosset, J. 1977; Li, Y., & Audétat, A. 2013).With the increasing technology of comprehensive utilization of resources,varied plants can now process different gold ores with various occurrence states(Neesse, T. 2014; 7. Ogundare. et al.2014)."

Jan 1, 2018

By F. Q. Dong

According to the principle that should be originated from nature, compatible with nature, used in nature and back to nature and based on conception of designing of eco-material, the author combined the ideas of material, environment, zoology and healthy. Properties of natural mineral materials were used to produce micro-aggregate elements by bionic method, so its components and function could accord with living environment. Eco-mineral functional materials which can adjust, purify and optimize the microclimate were reviewed. The authors pointed out the multifunction, com-pounding, the compound characteristics and integration regularities of micro-aggregates. It was the first time in the world to put forward the ?gene? technique or ?material chip? technique of manufacturing function micro-aggregates and eco-function elementary materials. The results of this re-search supported by the national ?863? Hi-tech Project, mainly including the high-efficient air purifying mineral compound material indoor, the clay elementary antibacterial materials, the masonry cement/coating/putty/compound with preventing radon radiation, environmental friendly composite functional coatings, mosquito repellent and healthcare material and zeolite-based energy-saving composite materials, were introduced. Finally, the foreground of mineral materials in the field of future advanced eco-friendly materials was also discussed.

Jan 1, 2014

The molybdenum ores currently utilized in China are mostly molybdenum sulfide ores whereas oxidized molybdenum ores, being finely disseminated and difficult to process, have not been exploited and utilized effectively. In this article the beneficiation process of a molybdenum ore occurred in an oxidized ore zone was investigated in order to provide a new way for the development and utilization of the oxidized molybdenum ores in China. The molybdenum mineral in the ore was mainly wulfenite and the associated minerals included barite, limonite, quartz and small amount of cerusite. Limonite in the ore occurred in a crust and honeycomb-like colloidal state and composed the framework for the formation of the other minerals in the ore, which filled the pores in the framework. Wulfenite was mainly fine-grained and occurred in the fine porous crust and honeycomb-like framework. The finely disseminated ore structure made the separation and recovery of the molybdenum mineral in the ore very difficult. On the basis of the mineralogical study of the ore, experiments were conducted to compare the various mineral processing methods for the beneficiation of the ore, including single gravity concentration, single magnetic separation, single flotation, and a combination of high intensity magnetic separation and gravity concentration. The results indicated that with single gravity concentration a molybdenum concentrate containing 5.85 % Mo with a yield of 11.76 % and a Mo recovery of 43.5 % was produced. With single high intensity magnetic separation it was very hard to obtain a molybdenum concentrate product. With single flotation process a molybdenum concentrate containing 7.06 % Mo with a yield of 15.14 % and a Mo recovery of 62.63 % was produced. With a combination of high intensity magnetic separation and gravity concentration a molybdenum concentrate containing 6.46 % Mo with a yield of 11.81 % and a Mo recovery of 42.11 % was produced. In conclusion, compared to the other methods the flotation process can produce more reasonable technological and economical results and is the best process for the exploitation and utilization of the finely disseminated oxidized molybdenum ore.

Jan 1, 2014

By Z. Q. He

This paper introduces the structure and working principle of SLon magnetic separator that has excellent performance in iron removal, and summarizes a part of the examples of applications, which applies this machine to remove iron from non-metallic ores, and shows widespread prospect of application of this machine in the purification of non-metallic ores.

Jan 1, 2014