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By F. Czerwinski

Mechanically fragmented chips of an AZ91D magnesium alloy were transformed into a semisolid slurry within the Thixomolding® system. Microstructural analysis of a material at various processing stages revealed that the cold deformation of the alloy, experienced during chipping, led to the recrystallization and growth of equiaxed grains which were subsequently converted to the globular structures by melting the grain-boundary network.

Jan 1, 2004

By W. A. Lang

"IntroductionCARBONIZATION, gasification, and chemical utilization of coal are interrelated topics, which makes it difficult to review one without indicating its connection with the others. Hence, in Progress in Coal Technology, Series No. 5: Carbonization, reference was made to gaseous products recovered in the carbonization of coal, and .to a number of chemicals made from the tars, light oils, and ammoniacal liquors which are by-products of coal carbonization.In this, the sixth paper in the review series, prime consideration will be given to the complete gasification of coal to give a fuel for domestic industrial, or power purposes and a synthesis gas suitable for the manufacture of gasoline, Diesel oil, and chemicals. The hydrogenation of coal, an alternative source of liquid fuels and of chemicals, will be reviewed, as will be a number of processes for •the recovery of chemical products from coal by extraction and chemical treatment."

Jan 1, 1952

By D. Song

In this paper, the differential equations governing the mass transport and the electrochemical reaction in a cathode catalyst layer of polymer electrolyte membrane fuel cells are solved based on the polynomial series expansion method. Explicit expressions for the polarization curve as well as for the distributions of oxygen, current density and overpotential are obtained when a quadratic, cubic or quartic polynomial is employed to approximate the oxygen concentration distribution. These kinds of explicit solutions are desirable for MEA design and diagnosis purposes. The comparison between the conventional numerical approach and the explicit solution approach proposed here shows that satisfactory accuracy can be reached by the first four terms of the polynomial series. The effect of the catalyst layer thickness on the accuracy of the obtained explicit polynomial solutions is also discussed.

Jan 1, 2005

By Roger T. Laine

"The Carswell structure, located in the western part of the Athabasca Basin, northern Saskatchewan, has been extensively explored since 1967. This exploration has been successful and lead to the discovery, in 1970, of the D sandstone-hosted unconformity related deposit. By the end of 1984, five additional basement-hosted unconformity related deposits had been delineated: the OP and N discovered in 1970, the Claude in 1971, the Dominique-Peter in 1981, and the Dominique-Janine in 1984. The D deposit has been mined out; the Claude open-pit has already produced more than 500 tonnes of uranium, the development of the Dominique-Peter underground mine (first phase) has been completed, and production from the latter started in 1985.All six deposits are located in the southern part of the Aphebian metamorphic core, 18 km in diameter, which has intruded at least 1250 metres of Helikian Athabasca Group sediments during a cryptoexplosion event at 480 Ma, unrelated to the emplacement of uranium mineralization. The metamorphic rocks, affected by the Hudsonian Orogeny, are divided in two lithostratrigraphic units: the Peter River gneiss, aluminous gneiss series, and the Earl River complex, mixed quartzofeldspathic and mafic gneiss series. A well developed regolith profile is recognizable in the south along the contact with the sandstone and inside the metamorphic core sometimes associated with conformable sandstone beds.Basement and sandstone-hosted uranium deposits show many similarities:-linkage to unconformity;-mineralogy and geochronology with a first phase mineralization characterized by a polymetallic sulphide-uraninite-brannerite assemblage dated at 1150 to 1050 Ma, a second phase characterized by a simple sulphide-uraninite assemblage dated at 890 to 820 Ma, and a third phase characterized by a pitchblende-hematite dated at 380 Ma; and,-linkage to early Hudsonian structures with remobilization of these structures during intense hydrothermal alteration resulting in Mg chlorite-illite halos."

Jan 1, 1986

By A. Staley, W. J. Cashwell, M. S. Moats

In the 1990’s, Técnicas Reunidas developed the Modified ZINCEX® Process to recover zinc from ores and secondary materials. The heart of this process was the use of solvent extraction to produce purified zinc electrolyte instead of traditional zinc dust cementation. This development was commercialized by Reunion Mining and Anglo American for primary ore at the Skorpion mine in Namibia with the first SHG zinc produced in May 2003. Horsehead Corporation through Horsehead Metal Products, Inc., its wholly owned subsidiary, is presently commercializing the MZP for the treatment of Waelz oxide. This paper will review open source information about the lessons learned and process modifications that have occurred at Skorpion over the past decade. It will also provide an update on Horsehead’s facility being constructed in Rutherford County, North Carolina.

Jan 1, 2014

By M. Staite

This paper analyzed the feasibility of converting a 5kW natural gas SOFC power generator system designed to operate on natural gas to be fuelled by methanol. The analysis included laboratory methanol fuel processing experimentation, methanol reformate SOFC cell testing, and SOFC system mass and energy balance modelling. Methanol fuel processing experimentation indicated that theoretical reformate compositions can be achieved for high temperature (600-900°C) methanol steam reforming. A 6% open circuit voltage decrease and a 10% peak power current density decrease between cell operation on humidified hydrogen and methanol reformate was observed. SOFC system mass and energy balance modelling indicated that a natural gas SOFC system can be converted to operate on methanol fuel with minimal (1%) efficiency impacts, however the systems' thermal integration can be impacted.

Jan 1, 2005

By G. C. Bateman

THE cause of silicosis and its prevention have held the attention of medical men and mine operators for many years and at the present rime the study of this disease is more than ever to the fore, even though a considerable abatement in the incidence of silicosis has been noted of late. This abatement is due to individual and collective efforts. The Industry is keenly alive to the situation and much research is being carried on. Silica dust is assumed to be a contributing factor in the cause of silicosis. How it acts progressively in the early silicoric is nor fully understood. As the study advances, more effective measures of control may be evolved. At present the Industry has three known methods of reducing the incidence: 1. By thorough X-ray examination of all applicants, with special reference to chest conditions. Those who are considered to be susceptible to the disease are prevented from entering the industry. 2. Thorough ventilation of the mine. 3. Control of tuberculosis in mining centres and removal of miners when first symptoms of tuberculosis become apparent. In 1934, the Ontario Mining Association formed a Committee, known as the Technical Silicosis Research Committee, to study and supervise work on problems related to silicosis. This Committee obtained the full-rime services of a mining engineer to carry our research work at the mines in the Province of Ontario. The Ontario Mining Association has also provided funds for the purpose of carrying on research work along pathological and biological lines. This work is being done in the Department of Medical Research of the University of Toronto, in the Banting Institute, under the supervision of Sir Frederick Banting. The Silicosis Committee work in full cooperation with the doctors in the Banting Institute and provide material from the mines for the it use.

Jan 1, 1936

By Isabel C. B Rodrigues, Flávia D. Reis, Versiane A. Leão, Rosa M. F. Lima

Attention has been focused in recent decades upon the precipitation of metal sulphides from acid mine drainage (AMD) and pregnant leach solutions, due to the advantages of the sulphide precipitation process over traditional methods employing hydroxides. The aim of this work was thus to explore technologies for copper precipitation using either Na2S or biogenic sulphide. The recovery of copper sulphide was improved when the initial pH of the solution containing each metal was 4 or excess sulphide was employed. In such, a condition the removal efficiency was 99.9%, corresponding to a residual level of 0.1mg/L for copper in solution. Kinetic parameters for precipitation were determined from the particle size distributions using the method of moments, where the growth and nucleation rates, as well the agglomeration kernel, were calculated. The biogenic sulphide was a suitable alternative to sodium sulphide for copper removal as either sodium sulphide and biogenic sulphide can be utilized to precipitate such a metal allowing the effluent to be compliant with environmental legislation.

Jan 1, 2014

By Xiang-dong and Zhu, Xia-jie Hao, Yi-lin Fan, Quan Jiang, Lian-xing Hu, Xia-Ting Feng, Shao-jun Li

"Columnar jointed basalt (CJB), which typically originates from lava flows, is characterized by a special geological structure. The joint network inside the CJB is self-organized into a rough hexagonal arrangement. The field test and measurement during the unloading excavation showed that the columnar joint sets and other internal joint sets not only are important for determining the mechanical properties of the CJB, but also induced its asymmetric unloading deformation and failure. A constitutive model, which considered mechanical deterioration of both the joint sets and rock blocks, was also developed to simulate the unloading behaviour of the CJB. The crack-confinement supporting method for surrounding CJB was developed to overcome the failure of columnar jointed rock mass in the diversion tunnel. Application to the CJB segments of the diversion tunnels in the Baihetan project indicated that this supporting method was reasonable and efficient. INTRODUCTIONColumnar jointed basalt (CJB) rock mass, which typically originates from lava flow, is characterized by a special joint structure. The joint network of the CJB is self-organized into a roughly hexagonal arrangement and leaves behind an ordered colonnade. The widely accepted current view regarding the formation of columnar jointing involves a thermally induced contraction–cooling mechanism (Peck and Minakami, 1968; Degraff and Aydin, 1987; Budkewitsch and Robin, 1994; Lore et al., 2000; Goehring et al., 2006). Although the columnar basalt formation mechanism is fairly understood, the geotechnical characteristics of such rock mass are not well established. In practice, joint sets always induce the multi- failure modes of surrounding rock in the tunneling space (Ibarra et al., 1996; Waltham and Swift, 2004; Mahendra and Bhawani, 2008).According to conventional wisdom in rock mechanics, structural joints affect the mechanical response of rock mass by introducing strong anisotropic effects (Barton and Bandis, 1980; Hudson and Priest, 1983; Brady and Brown, 1985). The columnar jointed rock mass should be considered an anisotropic material given that the joint sets are distributed with some principal directions and characteristic spacing distributions (Cundall and Fairhurst, 1987; Hoek et al., 1998; Wu and Wang, 2001; Budetta and Nappi, 2011; Fortsakis et al.,2012). Columnar jointed rock mass would result in structurally controlled failure patterns, even serious disasters during underground excavation because of the low shear and tensile strengths of intensely joints (Gencer,1985 ;Ishida and Uchita, 2000; Jia and Tang, 2008). The CJB rock mass in the Baihetan hydropower station has exhibited serious stability issues, including sliding, fracturing and even collapse (Shi et al.,2008). Therefore, the geotechnical and geomechanical characteristics of such rock mass should be assessed through in situ investigation and numerical analysis to minimize future accidents during underground unloading excavation."

Jan 1, 2015

By K. El-Ouassiti, M. Zouadi, C. Bazin, D. Hodouin

Data reconciliation techniques are used to attenuate the effect of measurement errors and estimate unmeasured variables. This paper illustrates the application of data reconciliation to hydrometallurgy processes using measurements from leaching and solvent extraction obtained from laboratory experiments. The application of data reconciliation provides an efficient way to detect gross and systematic errors and produces reliable performance indices for process evaluation.

Jan 1, 2005

By M. Rafati

In this investigation, the effects of T4 and T6 heat treatments of AZ91 magnesium cast alloy have been studied. The effects of different microstructural details such as morphology, size and distribution of precipitates and their influence on fracture mechanisms were investigated by optical and scanning electron microscopy. The mechanical strength of the alloy after T6 treatment was found to increase in comparison to the T4 treatment, due to the formation of discontinuous precipitates in the grain boundaries. Precipitation in this alloy occurs in two ways: continuous precipitation, which nucleates and grows inside the grains, and discontinuous precipitation, which forms at the grain boundaries. During ageing, the length of the continuous precipitates increases, and, hence, interprecipitate distance decreases. The formation of discontinuous precipitates causes initiation and propagation of cracks at and the weakening of the grain boundaries. This is the principal reason for the reduction of the ultimate tensile strength in T6 heat treatment in comparison to the T4 condition.

Jan 1, 2006

By B. S. W. Buffam

"The property of Aunor Gold Mines, Limited, is in Deloro township, Ontario, about 3 miles southeast of Timmins. It consists of a group of eleven claims between the Buffalo Ankerite and Delnite mines.In the autumn of 1909, two brothers, John A. and W. S. Mitchell, joined the 'gold rush' to Porcupine. By the time they arrived the township of Tisdale, in which the Hollinger and Dome discoveries had been made, was staked solid but they managed to locate four claims in the northern part of Deloro township. Sufficient surface work was performed to bring the claims to patent in 1915. Following the Porcupine fire the Mitchells left the north to follow the oil developments in southwestern United States. In 1935 because of the rise in the price of gold and the successful development of the l3uffalo Ankerite and Delnite mines, they returned to Timmins and organized Augite Porcupine Mines, Limited, which combined the original four claims in Deloro and two adjoining claims controlled by Montreal River International Silver Mines, Limited. There were few rock exposures on the property, and as the overburden was generally deep surface exploration was impracticable. A programme of diamond drilling was, there; fore, undertaken in an endeavour to locate the western extension of the orebearing formation of the Buffalo Ankerite mine. This drilling was started in August 1936, and 5 months later ore was intersected at a depth of 500 feet on the south boundary of the property."

Jan 1, 1954

By F. H. Edmunds

LLOYDMINSTER is the centre of a well developed agricultural area, lying on the Alberta-Saskatchewan interprovincial boundary in Township Fifty. The surrounding country is gently undulating, without any notable topographic features, but twenty-two miles to the north the North Saskatchewan river, and thirty miles to the south the Battle river, have cut deep valleys. In the spring of 1934, a wild-cat well (Lloydminster Gas Company's No. 1 well) was successful in striking a large flow of gas at a depth o 1,974 ? feet. The gas was piped into the town, a short distance south, and Lloyd-minster became the first Saskatchewan town to be served with natural gas. Following this discovery, other wells were sunk and, up to the present, thirteen wells have been drilled m what is here designated the Lloydminster area. Ten of these wells are in Saskatchewan and three in Alberta. Seven were successful in obtaining gas, three oil, and three have been unsuccessful. The area tested by this drilling is about eight thousand acres, six thousand of which can be considered as proved gas or oil land. To the south and west of Lloydminster, in the Province of Alberta, there are several areas in which oil and gas have been discovered. The Wainwright field lies nearly fifty miles to the southwest; Battleview, where recently gas has been discovered, is thirty miles west-southwest; and the Ribstone area is about thirty miles south and a little west. At Ribstone, a number of wells were drilled some years ago and there is a small production of oil. The data relating to the wells in the Lloydminster area that are recorded in this paper are taken from the records of the several companies operating in the field. The names of these companies are given on the map and on the type stratigraphic section (Figures 1 and 2). The author wishes to record his appreciation to Mr. R. H. Shaw and Mr. 0. C. Yates, both of Lloyd-minster, for much valuable information; also to Mr. E. Swain, of the Department of Natural Resources, Regina, with whom the writer has visited the field on several occasions, and who, by his enthusiasm and encouragement, has done much to forward the development of the area. The well samples were examined at Ottawa by officers of the Borings Division of the Geological Survey of Canada, who also made the interpretations of the logs. Frequent references will be made to the work of Dr. G. S. Hume, of the Geological Survey, and the writer would like to pay tribute here to his work.

Jan 1, 1940

By K. Krishnapisharody, S. Clark, M. Barati

Different gas purging methods to metallurgical baths have been applied to date, among which are top lancing and bottom blowing through tuyeres or porous plugs. Among these, the porous plug bottom blowing technique has shown higher efficiency in gas utilization than tuyeres and top blowing, due to smaller bubble size and lower liquid velocity. However, the studies related to bottom stirring of metallurgical baths are limited to slag-less or thin slag-covered melts. In particular, there is no examination of stirring ability in conditions similar to Falconbridge's Slag Make Converter, where the bath is covered with a thick slag layer and a stream of solids is charged on the bath from top. This study was undertaken to investigate the application of gas purging through a porous plug in stirring in and melting of the solid feeds. The spreading behaviour and melting time of a solid layer forming on a plume created by stirring were calculated using the existing models. The results show that formation of a thick solid layer, specifically in areas beyond the plume region is very likely. Nevertheless, the thickness of the layer and melting time do not appear unreasonably high. It is predicted that by proper controlling of gas flowrate and plug configurations, successful solid charging through the mouth can be practiced.

Jan 1, 2007

By Walter Greaves

THIS paper describes a series of tests performed at the Hollinger mill during the past four years, in which both metal and rubber-lined pumps were used for pumping sand and slime. While conditions will not be the same at other mills, it is felt that the information gained from the tests should be of value to other operators and of assistance to them in selecting the most efficient size of pump and kind of lining for economical operation. For the successful operation of pumps with rubber linings there are certain conditions, which, if recognized at the outset, will save the operator a good deal of work and trouble. First is the necessity of keeping sharp pieces of steel, or anything that might cut the lining, out of the pumps. This can be effected by placing screens in the proper locations. Second is to recognize the fact that the rubber lining of the shell, and the rubber cover of the impeller, are subjected to very different conditions. The shell lining, :being at rest and well supported by the metal case, has a relatively easy job compared ? with the impeller covering, which is subjected to centrifugal force and has a tendency to tear itself away from the metal core. Also, the pulp travels through and past the impeller at a high velocity. These two factors, centrifugal force and velocity of the pulp, would appear to set a limit to the speed at which, for a given set of conditions, it is economical to run a rubber-covered impeller. Therefore, a pump should be large enough for the work to be done. To get the best mechanical efficiency, it must be operated somewhere near the limit of its capacity, but this may not give the best overall cost, because the saving in power, due to the high efficiency, may easily be lost through excessive wear on the lining. It would appear that this condition is more critical in a rubber-lined pump than in one lined with metal.

Jan 1, 1939

By L. M. Wang, G. P. Jiang, Y. Jiang, Liao. W. S.

ABSTRACT The authors measured porosities and permeabilities for cores from a low-permeability sandstone uranium deposit in Inner Mongolia. Features studied included fine pore structure, mineral composition, cation exchange capacity, granule appearance, and cementing features. In general, grading of the grains was relatively poor, which decreased the radii of the pore channels. The pore throat distribution was significantly heterogeneous. Pore channels ranged from small to large, but the lack of large pore channels led to low permeability. Cementation by calcite and clays, including montmorillonite, chlorite, and kaolinite, resulted in pore channel narrowing, further decreasing the permeability of the formation.

Jan 1, 2014

By J. B. Watts

"THE Mine Engineering Department at Gaspe Copper is staffed by a chief engineer, assist-ant engineer, research engineer, chief surveyor, four instrument men, chief bonus clerk, draftsman, and a helper pool of four permanent men plus one or two students in the summer. The men are grouped according to function for organization purposes. Routine services provided by the Mine Engineering Department in-elude ail surface and underground surveying and mapping, preparation of working drawings, compilation of engineering reports, recommendations on ventilation, testing the mine air for carbon monoxide, research on mine equipment and its use, and the calculation of incentive bonus. Demand jobs from departments other than the Mine Department .are done on request. Such jobs may be in the plantsite, the Town of Murdochville, or at the shipping points at Gaspe harbour or the St. Lawrence river."

Jan 1, 1959

By V. I. Ryaboy, S. A. Kondratyev

"The paper describes influence of desorbed species (DS) of a number of xanthates and higher dialkyldithiophosphates on the collective ability of these reagents. Adsorbed on mineral DS of the reagents in the form of products of non-stoichiometric interaction between xanthates and heavy metal salts can pass to the gas–liquid interface and remove liquid from the layer between mineral particle and water surface. A high-speed video recording displays the process of spreading of DS of xanthates and dialkyldithiophosphates over water at the moment of local rupture of the water layer. Expansion of “dry” spot on the mineral surface after DS of xanthate capture and displace liquid from the layer has been proved with video images. The comparative analysis of collecting ability and dynamic surface activity of dialkyldithiophosphates shows that these characteristics are in good correlation. The forces exerted by spreading film of the reagent’s DS on liquid in the water layer are evaluated, and the water flow rate from the layer is determined. The line of the reduction in thickness of the water layer behind the front of spreading film of DS of dialkyldithiophosphates and xanthates coincides with the line of the increase in their dynamic surface activity. Their force on the liquid volume in the water layer characterizes collecting ability of the DS film of xanthates and dialkyldithiophosphates. It has been supposed that the collecting ability of DS of a reagent is a part of its overall flotation activity, conditioned by surface tension of solution and, thus, defined by the structure of hydrocarbon fragment of the reagent.INTRODUCTIONIt is believed that collecting ability and selectivity of collecting reagents is mainly governed by adsorption of a reagent at the solid–liquid interface. A few studies have shown that activity of collecting reagents at the gas–liquid interface may have deep influence on their collecting capacity and selectivity. Experimental researches have revealed correlation between surface pressure in a carboxylic acid film on liquid’s free surface and floatability of useful components (Kulkarni & Somasundaran, 1975; 1980; Quast, 2006). According to Quast (2006), it is not always that surface pressure of a reagent film influences collecting ability of carboxylic acid. For instance, pH range of adsorption of tetradecanoic acid on hematite does not coincide with pH range of high surface pressure. So, surface properties of this acid contribute little to flotation efficiency.The correlation between reagent film surface pressure and mineral floatability has been reveled for quartz and cationic reagents, too (Bleier, Goddard, & Kulkarni, 1977). Finch & Smith (1973) showed that combination of adsorption of ion–molecular amine complexes on mineral surface and high surface tension of “fresh bubbles” was favorable for flotation performance. The use of bubbles with reduced surface tension resulted in a decrease in quartz floatability."

Jan 1, 2016

Roasting of molybdenite concentrate is an important stage in the production of commercial molybdenum trioxide. The oxidation kinetic and mechanism of molybdenum sulfide concentrates from two plants were investigated at temperatures from 444 °C to 640°C. The rate of reaction was determined for thin layer samples in a muffle furnace at controlled temperatures, oxygen excess and removal of sulfur dioxide. For both concentrates the rate of reaction is fairly slow at temperatures below 500°C and remains fairly constant from 540 to 600 °C. It was observed that the concentrate from the first plant presents a tendency for sintering or glazing at temperatures above 620°C, whereas the same phenomena was observed at 20 or 30 °C higher temperature for the second concentrate. A kinetic model of two reactions, involving the formation of Mo02 as intermediate oxide for the production of Mo03 is proposed and activation energies of 23.0 and 20.8 kJ/mol for the first and second reaction were calculated for temperatures between 520 °C to 600 °C. These low values of activation energies indicate that the overall rate of oxidation is controlled by mass transfer, particularly in a porous layer of oxides. Therefore, the renewal of the surface by mixing and motion of the concentrate layer is of great importance. Sublimation of Mo03 becomes significant for temperatures above 650 °C.

Jan 1, 2007

By Hong Zhong, Shuai Wang, Fangxu Li, Guangyi Liu

"The flotation performances and adsorption mechanisms of a-hydroxyoctyl phosphinic acid (HPA) to malachite, cassiterite and wolframite were investigated by micro-flotation tests and X-ray photoelectron spectroscopy (XPS) analyses. The micro-flotation results indicated that compared with styrene phosphonic acid (SPA), diphosphonic acid (DPA), benzohydroxamic acid (BHA) and salicylhydroxamic acid (SHA), HPA exhibited excellent collecting power to the three oxide ores. In addition, HPA showed superior selectivity against hematite, tourmaline, feldspar and quartz. The results of XPS analysis demonstrated that HPA reacts with active species (M) on metal oxide by formation of P-O-M or P-M bonds.INTRODUCTIONIn mineral processing, flotation has been the main process for separation and recovery of valuable minerals from complex ores (Mei, 2013; Zhou, 2014). One of the key requirements in flotation process is to increase selectively the surface hydrophobicity of the targeted minerals by surfactant (known as collector in flotation) adsorption so that these mineral particles can preferably attach air bubbles in a slurry or pulp (Bai, 2004; Hankins, 2004). To anchor a solid surface selectively, special functional group are designed to adjust the interaction between the surfactant and the active sites of solid surfaces (Wu, 2006; Huang, 2014).Organic phosphorous compounds have strong affinity toward metals or metal oxides because they form more stable metal complexes than metal carboxylates (Pazik, 2001; Zheng, 1998). In mineral engineering, phosphorous compounds have been exploited as metal extractants and flotation collectors (Alguacil, 2002; Sun, 2008). Ni (2012) and Zhang (1998) introduced diphosphonic acid (DPA) as an effective collector for flotation of fersmite and niobite. Liu (1999) found styryl phosphonic acid (SPA) was a superior collector for flotation recovery of finely disseminated rutile ores. Gruner and Bilsing (1992) thought SPA was one of the best collectors for flotation recovery of cassiterite which could obtain a high-grade concentrates of more than 40% with high recovery values. Bulatovic (1999) investigated the flotation performances of phosphoric acid ester (PAE) to perovskite, ilmenite and rutile and found that PAE was an impactful collector for selective flotation of titanium minerals from complex ores in the presence of petroleum sulfate. However, a-hydroxyoctyl phosphinic acid (HPA) as a flotation collector for recovery of titanium ores were hardly reported in the previous literatures."

Jan 1, 2016