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By D. Schleiss

Reduced access to knowledgeable workers is creating challenges for operations. We are doing more 4D Operations - dirty, dull, dangerous, and distant. Personnel costs in these environments are high, and it is not always possible to get the people where you need them. Integrated Operations is a strategy to integrate people, process, and technology for faster and better decision making. Adopting an integrated operations approach can help to relocate personnel, improve collaboration, and align objectives to deliver reduced costs and improved performance. In this paper, the authors will highlight the required infrastructure to enable an Integrated Operations platform. Key decision points for enabling this technology for both Greenfield projects and existing mines will be discussed. Furthermore, the benefits and improved return on investment that result from deployment of an Integrated Operations strategy will be presented.

Jan 1, 2014

By Peter Radziszewski

"Comminition process costs, which typically represent an important contribution to mining operating costs, can themselves be divided roughly between energy and liner /charge wear. As such, developing the ability of predicting mill wear will allow a more accurate estimation of wear costs and therefore their control. In this paper and based on the possibility of estimating energy dissipated in impact and abrasion by using a discrete element charge motion model for mill charge motion simulation, media wear will be investigated principally as a function of three wear mechanisms : impact, abrasion and corrosion. Experimental results will be used to identify a total media wear model. Model results will be compared with real mill data from three operating Australian mines. These preliminary results show for the cases tested that the overall average error, as compared with the observed cases, is 0 % with a standard deviation of 66.1 %. Results from the Bond abrasion index tests, for the same cases investigated, give an overall error of 73 % and a standard deviation of 192.5 %. Further work is in progress to improve test procedure, validity and confidence.INTRODUCTIONComminition process costs, which typically represent an important contribution to mining operating costs, can themselves be divided roughly between energy and line / charge wear. In Greenfield situations where the estimation of operating costs is critical in determining project feasibility, the level of confidence in such estimates becomes quite important. With regards to media wear, the Bond abrasion test currently serves as the standard media wear prediction device. However, as shown [l, 21 test results once compared with actual wear rates can vary greatly. Figure 1 shows test results as compared with 15 cases. Average error over this data is 73 % with a standard deviation of 192.5 %. As such, developing the ability of more accurately predicting mill wear will allow greater confidence in wear cost estimation and therefore their control."

Jan 1, 2001

By W. J. Taylor, T. D. Parris

"Over 90,000 feet of raise have been bored at International Nickel underground mining operations throughout the Sudbury District since the advent of raise boring in the early part of July, 1964. With a total of 10 raise borers on hand at this time, techniques have improved steadily since introduction at INCO mines. The first unit, designed for use in rock of low compressive strength, had to be modified and redesigned to cope with Sudbury Area Precambrian rock. As equipment and boring techniques improved, a specially designed machine for larger holes was developed and is now in use. More powerful units, with a thrust capacity of up to 750,000 pounds, are under investigation. Raises have been bored up to 84-inch diameter, and the changeover to 5- and 6-foot flat reaming heads with improved cutter design has increased performance substantially. As a result, 5-foot-diameter raises have been completed to a length of 750 feet and 6- and 7-foot raises to over 500 feet. Reference is also made to the drilling of over 23,000 feet of drainage and sand-fill holes, ranging up to 7% inches in diameter, with smaller underground rotary drill equipment.Finally, a look into the future indicates the need for further improvements in equipment design to permit economic boring of 7- to 8-foot-diameter raises in Sudbury Area ground types."

Jan 1, 1972

By Dominic Fragomeni

"The mineral processing industry has had a long history of innovation that is recognized but not often celebrated. These include significant advances in mineral measurement, testing, comminution, mineral separation and process control technologies that have transformed mineral assemblages into ore.This presentation presents some of the major mineral processing innovations and the impact they have had on our industry. As we look to the future, it is critical that we innovate and change. We will explore some examples of the next developments and how they can be catalyzed in the face of risk management, lower metal price cycles, resource constraints, inertia and the challenge of short term value delivery."

Jan 1, 2017

By P. N. Saavedra, E. A. Salamanca

"The maintenance strategies in the mining industry are changing from operative and periodic inspection strategies to a condition-based, predictive maintenance strategy centred in vibration analysis plus complementary techniques. Condition monitoring can also help to improve availability by being able to pinpoint and diagnose problems on operating machinery at an early stage. This reduces unscheduled downtime and production losses.However, in mining, for shovels operating in transient modes, with variable load and/or speed, the FFT (Fast Fourier Transform) standard approach is not directly applicable for analysis. This work illustrates how spectral order analysis and new transforms, called time-frequency transforms (TFT), allow us to monitor the shovel when it is working. Some practical examples showing the application of these analysis techniques to occasional vibrations measured on hoist and crowd transmission of a shovel are also presented. It is shown that at present, it is possible to carry out the vibration monitoring in the mining shovel while it is working, therefore avoiding the high cost of a loss of production which can occurr in traditional monitoring, where the measurement is taken while the shovel is out of production."

Jan 1, 2002

By T. Gammatikopoulos, C. Gibson, M. Aghamirian

Lithium is an alkali metal found in brine deposits in the United States, Chile and Argentina, as well as in hard rock deposits in Australia and North America. In hard rock deposits, spodumene (LiAl(Si2O6)) is the major economic lithium bearing mineral. Spodumene is typically upgraded through a combination of dense media separation, flotation and magnetic separation. One of the major spodumene concentrate quality specifications is the iron oxide content because it will help determine if the concentrate is considered ceramic grade for use in ceramics and glass or chemical grade for use in lithium ion batteries. The rejection of iron bearing silicate minerals from artificial ore composites (high amphibole and low amphibole, high quartz/feldspar) from a hard-rock spodumene deposit was investigated using magnetic separation and flotation. The efficacy of Wet High Intensity Magnetic Separation (WHIMS) in iron rejection was found to be dependent on the mineralogy of the iron-bearing silicate minerals including modal distribution, liberation and association. When magnetic separation was conducted prior to flotation, the Fe2O3 grade in the final flotation spodumene concentrate was reduced from ~3% to ~1% Fe2O3 , and improved lithium recovery in flotation was observed. It was determined that it was most effective to conduct WHIMS on the flotation feed after scrubbing and de-sliming because this reduced the required magnetic field to recover iron-bearing minerals, likely because slime coating was greatly reduced. Flotation collector screening of four different collectors with varying rosin acid content demonstrated a potential increase in selective flotation of spodumene over some iron silicate minerals with decreasing rosin acid content in the fatty acid collector. However, due to marginal difference in flotation results with the various collectors tested, further testing is required to confirm the observations made and establish a hypothesis regarding the effect of rosin acid content.

Jan 1, 2017

By Andy Cole, Ken Thomas, Stephen Durn, Jacques McMullen

"The roasting and gas handling circuits of the Barrick Gold’s new Roasting Facility at the Goldstrike Mine in Nevada, USA incorporate well proven technologies in a unique combination. During the design of the plant, every effort was made to utilize the best available technologies from the perspective of capital, environment and operating costs.Product from the up-stream dry grinding circuit requires roasting to maximize gold recovery. The roaster utilizes Freeport-McMoRan whole ore roasting technology with pure oxygen as the oxidizing gas. This process was chosen based on its proven application on Carlin-type “double refractory” ores. Double refractory is indicative of the gold being difficult to direct leach due to a combination of pyrite encapsulation and the carbonaceous preg-robbing of the ore.A very extensive gas cleaning train follows the roaster and comprises direct cooling, dust scrubbing, indirect cooling, wet electrostatic precipitation, mercury scrubbing, SO2 scrubbing, CO incineration and NO, reduction before venting to the atmosphere.The roasted calcine is quenched, neutralized and then thickened before leaching in the carbon-in-leach-circuit.INTRODUCTIONBarrick’s strategic development plan integrated the production of gold from Goldstrike’s carbonaceous ore reserves by 2000. A due diligence review of carbonaceous ore processing options was initiated during the second half of 1 996. Processes considered included autoclaving followed by a proprietary ammonium thiosulfate leaching process, fine grinding/autoclaving as practiced then by Santa Fe, and whole ore roasting as practiced by then Independence Mining and Newmont. The objective by year-end was to recommend the most robust and economical process for Goldstrike’s carbonaceous resources. In the fall of 1996, a detailed review of roasting as a processing alternative for Goldstrike was initiated."

Jan 1, 2001

By J. Frostiak

"This paper describes some energy reduction measures Implemented at the Griffith Mine. Before proceeding, I will give you a brief overview of the operation.The Griffith Mine is an iron ore mining, concentrating and Pelletizing complex located in the red lake area of northwestern Ontario. The operation is owned by Stelco Inc. And is managed By Pickands Mather & Co. of Cleveland, Ohio. Operation of the concentrator commenced in 1968 and it has been producing at a nominal capacity of 1,500 ,000 tons annually.The plant flow sheet is illustrated in this slide. Run of the mine ore is crushed in a single stage 54"" gyratory crusher. Reclaim ore feeders draw from an open stockpile to feed two 32' diameter by 12' long autogenous mills, each driven by 6800 hp. Two s·rages of wet magnetic separation, roughers and cleaners, and primary cyclones complete the primary circuit. Cleaner concentrate is then ground in four 14' diameter by 28' long pebble mills rated at 2000 hp. The secondary grinding circuit is closed by cyclones and fine screens. Secondary cyclone overflow is further upgraded through hydro-separators, finisher magnetic separators and flotation.The magnetic concentrate produced is then thickened, filtered, balled and fired in three vertical shaft furnaces to produce a high quality hematite pellet."

Jan 1, 1983

By E. S. Yan, R. Graley

"The StackCell was developed to overcome the engineering and design challenges that are commonly associated with existing flotation technology such as pneumatic, self-aspirating cells, mechanical cells, and flotation columns. These challenges include high energy consumption, large floorspace requirements, and size. They are most evident when designing systems to process streams containing a high volumetric flow rate coupled with a significant float yield. Unlike many metalliferous and industrial mineral applications, fine coal flotation circuits are typically characterized by feed streams containing a low solids content (<5%, by weight) where up to 85% of the feed can report to the product launder. With input from major engineering houses and end-users, the Eriez Flotation Division (EFD) developed the StackCell technology with the goal of providing an additional flotation option for end-users. This technology was designed specifically to overcome these challenges by providing an efficient method of separation in terms of metallurgy, but also with respect to equipment size, energy consumption, and installed costs. Besides being placed in tandem with existing cells to provide cost-effective supplemental capacity, this technology can be installed in a stand-alone arrangement as recently demonstrated at Patriot Coal’s Kanawha Eagle preparation plant. This manuscript provides an understanding of the underlying fundamentals of this new technology and presents data from Kanawha Eagle in addition to other industrialscale installations.INTRODUCTIONOver the past decade, column flotation has continued to gain acceptance as an alternative method for recovering fine coal due to superior metallurgical performance as compared to mechanical flotation cells. This point has been proven on numerous occasions by comparison of plant flotation data with the release analysis separation curve (Dell et al., 1972). Data from a release analysis test approximates the ultimate flotation response of a coal sample. In North America, a number of investigations have been published that document bottom-line improvements achieved using column cells (Luttrell et al., 1999; Kohmuench et al., 2004; Baumgarth et al., 2005). According to these reports, the benefits are derived from an overall increase in plant yield that can be achieved due to the improved product grade in the flotation circuit. In particular, the application of wash water to a deep froth utilized in column flotation minimizes the nonselective recovery of high-ash ultrafines that are hydraulically entrained in the froth by conventional flotation machines."

Jan 1, 2013

By Walter S. Bergholz, Michael L. Schreder

"Since Escondida began operations in fiscal 1991, a series of aggressive expansion projects have enabled market share to be increased and ever larger profits to be realized. This was possible due to the very large size of the ore body and its high grade - averaging 2.7% copper from startup through fiscal 1997. The situation has now changed: ore grade is falling rapidly and is projected to be only 1.55% by 2003. Since revenue is directly proportional to ore grade, while costs are proportional to quantity of ore processed, profits will begin to fall dramatically. The Phase IV Expansion Project is intended to forestall this drop in profits by increasing ore processing capacity by over 85%.The Phase IV concentrator is designed for a nominal capacity of 110,000 MTPD and the key to achieving this value is through the proper design of the grinding circuit. This paper presents the general design criteria for the grinding circuit, as well as a description of the facility.INTRODUCTIONThe Phase IV Expansion Project consists of a new copper concentrator located 8.5 km south of the existing operations, a new tailings disposal and water reclaim system, a new concentrate slurry pipeline to the coast, and added concentrate handling capacity at the port of Coloso. The new concentrator has a nominal capacity of 110,000 tonnes per day (MTPD), compared to the existing concentrator’s capacity of 127,500 MTPD. The Laguna Seca concentrator is based on using the largest and most efficient ore grinding mills now available.The concentrator has been designed for a 110,000 MTPD nominal capacity. The process design criteria for the Phase IV project were established from in-house operating information and from test work. Unlike a green field project, Escondida already had an operating plant and it processes ore from the same pit that feeds the Phase IV plant. It is expected that the current mineralization will be similar for the first 6 years of operation of the new project. Therefore, some of the current plant operating conditions were incorporated directly into the design criteria."

Jan 1, 2004

By A. Uribe-Salas, J. A. Finch, B. J. Huls

Froth depth or interface level is an important control variable in column flotation which can influence both grade and recovery. A common method of locating the level is based on sensing the hydrostatic pressure at one or more points along the column. The level position is then calculated from these pressure readings using an equation which includes the bulk density in the froth and bubbling zones. The precision with which the level is detected depends on how well these density values represent both zones. The calculation of these bulk densities from theoretical considerations is not possible and, therefore, the practice is to estimate them by calibration. Unfortunately, the calibration parameters often do not report the level with an acceptable accuracy. A portable conductivity probe has been developed to detect the position of the interface from conductance measurements across the interface. The location of the interface corresponds to the position where a large change in conductance is observed, which is primarily a consequence of the difference in gas holdup between the bubbling and froth zones. This probe can be used to detect the position of the interface to an accuracy of± 5 cm. The probe can be used while the column is in operation, which allows the on-line calibration of the level detection system. Results obtained in its application in a pilot-scale column (0.91 min diameter) are described.

Jan 1, 1989

By Robert E. McIvor

"The design/optimization of the pump and cyclones to maximize grinding circuit efficiency first requires a concise understanding of, and clearly defined specifications for, desired grinding circuit performance. Subsequently, the pump and cyclone performances that provide the desired grinding circuit performance can be defined. Once the performance requirements of each process unit are determined, selection of physical equipment parameters that will deliver those performances can be carried out.The Functional Performance Equation shows that there are two distinct efficiencies in closed circuit ball milling. One of these, “Circuit Classification System Efficiency” (CSE), is the fraction of “coarse” material inside the ball mill upon which grinding energy is deliberately expended, versus the remaining fraction of “fines” or finished size material inside the mill, upon which grinding energy is wasted (on over-grinding). The role of the pump and cyclones is to maximize CSE, which is the desired grinding circuit performance. The obtainable target CSE for any given circuit can be estimated, for example, by referring to a plant data base of CSE’s. Design/optimization guidelines then allow us to specify the pump and cyclone performances that will achieve the target CSE.This paper outlines the step-by-step, systematic method of pump and cyclone selection which maximizes CSE. Numerous examples of its successful application are provided.THE FUNCTIONAL PERFORMANCE EQUATIONObservation of the feed and product size distributions going into and discharging from the mill in grinding circuits with low versus high circulating load ratios initially led to the definition of “Circuit Classification System Efficiency” (or CSE, McIvor, 1988a), and subsequently the discovery of the Functional Performance Equation (McIvor, 1988b; McIvor et al, 1992). The CSE is the fraction or percentage of “coarse” (usually in reference to the plus P80) size material inside the mill, versus “fines” or product size material finer than the circuit P80. It can be readily calculated by taking the average of the percentage of said coarse material in the mill feed and mill discharge streams. As this also represents the percentage of the mill energy expended on targeted, coarse size material, it is directly proportional to overall grinding circuit efficiency and production rate. This is all clearly expressed in the Functional Performance Equation for ball milling circuits, for which the derivation has often been presented (e.g. McIvor, 2006)."

Jan 1, 2011

By Larry A. Lien

"A brief summary of the different membrane separation options currently available to the mining industry will be presented and discussed. The processes described involve operating membrane plants on the following applications: pregnant leach solutions (PLS) in the copper and gold industries, fractionation and concentration of metals and acids in refineries, and wastewater treatments to meet state-of-the-art surface discharge criteria.Included is a specific discussion on cost savings resulting from an operating membrane treatment system of nearly 3,500 m3/hr barren water relative to the prior, conventional precipitation practice at a major heap leach gold mine. This Engineered Membrane Separation® (EMS®) plant has produced water for six years that has met all standards for direct discharge into the environment, and captures and returns to the operation valuable minerals and solvents which were not previously being extracted in the Merrill-Crowe process.INTRODUCTIONMembrane technology has been available for more than 35 years, but has been used sparingly in the mining industry. However, recent developments in polymer chemistry, spiral-wound element design and construction, water clarification pretreatment equipment and techniques, and an expanded understanding of membrane fouling and cleaning techniques have dramatically improved the reliability and robustness of membrane-based systems for potential use by the mining industry.In the past 15 years large operating plants have successfully demonstrated the use of this “new” membrane technology to include the separation of pay-metals from large-volume acid and cyanide heap leach mining solutions containing copper, zinc, gold and silver. Moreover, variations on these same membrane technologies are ideally suited to fractionations that add value to processing fluids from refineries, like separating metals from acids or concentrating acids and producing high-quality process fluids."

Jan 1, 2010

By A. Bamber

Canadian leadership in a global mining context will depend not only on entrepreneurship and best practice but also on technological innovation. This paper argues for more ambition and commitment to R&D for technological innovation in Canadian mining. It focuses on underground hardrock mining, where past R&D initiatives have simply not stood the test of time, and it is important to examine why. Concerns arise because industry’s commitment to R&D has not been sustained over time. Innovation through exploration, processing, and environmental technologies has been more significant. Meanwhile, R&D capacity and synergies in government institutions and universities have not been exploited. There is a need for more commitment, coordination, and collaboration by industry, governments, and universities. This paper examines some corporate models that have achieved sustainable innovation, along with some that have not. A strategy for innovation is discussed that relates to culture, commitment, coordination, and collaboration.

Jan 1, 2005

By Tassos Grammatikopoulos, Sarah Prout, William Mercer, C. Gunning

"The Nechalacho rare metal deposit is located in NWT, Canada. Avalon Rare Metals Inc. is now evaluating processing techniques for recovery of REE to be used in the industry. QEMSCANTM analysis coupled with whole rock, REE, Zr and Nb, and electron microprobe analyses were utilized to identify and quantify the mineralogy of the deposit, and define the REE distribution among minerals. QEMSCANTM mineralogy was performed on fifty intact drill samples using EXPLOMINTM that provided textural information for the mineralization; crushed samples were used to determine the variability of the ore and define REE domains, and composite samples to determine the liberation and association of the REE minerals. The sample matrix predominantly consists of biotite, feldspars, quartz, muscovite/clays, minor chlorite and amphibole, magnetite and hematite and carbonates. REE include in decreasing order of abundance allanite (3.6%), monazite (1.5%), synchysite (0.9%), columbite (0.9%), fergusonite (0.6%), bastnaesite (0.4%), and zircon 11.0%. The majority of the HREE are carried by fergusonite and zircon, and the LREE by monazite, allanite, synchysite and bastnaesite. QEMSCANTM mineralogical data is extremely valuable in assessing the mineralogy of the ore. The data have been implemented in defining the mineralogy of the ore body, support metallurgical test work, predict recoveries and grades, and finally calculate reserves of the deposit.INTRODUCTIONAvalon is in the unique position of owning and developing one of the world’s largest rare earth deposits in the Northwest Territories of Canada.The term Rare Earth Elements (REE) is used to describe the 15 lanthanide elements or metals and, more recently, the metals yttrium and scandium, which display similar physical and chemical properties. REE are not particularly rare and have a similar abundance in the earth’s crust to nickel, tin or tungsten. Unlike these better known metals however, the rare earths have little tendency to become concentrated into commercial ore deposits. When they do become concentrated, deposits of REEs usually display enrichment in one of two groups. The most commonly occurring deposits of REEs contain a sub-group of elements referred to as the “light rare earth elements” (LREEs), which include lanthanum, cerium, praseodymium, neodymium, and samarium. Less commonly, deposits of REEs contain the much more valuable sub-group of elements referred to as the “heavy rare earth elements” (HREEs), which include europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium. Yttrium and scandium most commonly occur in association with this second HREE sub-group. Generally, LREEs are produced from the mineral bastnaesite, and the HREEs have been produced from the minerals xenotime and monazite. LREEs continue to be produced from bastnaesite, however in the 1980s, China started production of HREEs from unique laterite clay deposits. China now produces approximately 95% of the world’s rare earths."

Jan 1, 2011

By Richard Jundis

At the Vale Inco Ontario Operations, the working environment is rapidly evolving with organizational changes, new business systems and software tools. These changes are required in order to meet today?s challenging business environment. Mining professionals are focusing on the development of safe and achievable mine plans to maximize mining value while reducing the potential of project delays and production shortfalls. This paper explores how new design tools, techniques and system designs in mine planning are being developed to optimize the value of every ton of ore mined and processed. To differentiate from other papers on long-term planning, this paper focuses on the concept of business planning at the mines. Business planning is the understanding and optimization of the relationship between mine plans and the value it adds in the overall process. The management and key stakeholders of Vale Inco have recognized that the development of a robust mine planning system and programs are essential for the long-term sustainability of the operations.

May 1, 2009

By Barrie Robb

Outline 1. Mackenzie Aboriginal Corporation (MAC) 2. ACR background 3. ?Learning from Experience? project - What - Why - lessons 3. How Industry could contribute to sustainable Aboriginal communities 4. Concluding words What is the Mackenzie Aboriginal Corporation (MAC)? ? Aboriginal owned ? Established construction capabilities ? Commitment to development of northern resources ? Partners have extensive experience

May 1, 2008

By Jan E. Nesset

It is just over 100 years since the practice of blowing small bubbles into a mixture of ground ore and water revolutionized the mining industry, resulting in uneconomic deposits becoming highlyprofitable mines, along with the inevitable lawsuits over this new technology called froth flotation. To this day, the viability of many mining projects rests largely with the ability of flotation to effectively capture the valuable minerals and reject wastes. Remarkably, bubble behaviour in flotation has not been well understood until very recently with the advent of new sensor technologies that can be brought directly into the operating plants. This presentation will review the importance to the mining industry of understanding bubbles, highlight these new technologies and illustrate, with examples, how paying attention to your bubbles will pay off.

Jan 1, 2009

By Julián M. Ortiz

Uncertainty quantification of a spatially distributed variable at any scale can be handled through geostatistical simulation. Large computation time, storage, and post-processing of the realizations are required to obtain a final assessment of block uncertainty. Multi-Gaussian kriging is a flexible alternative to simulation. The idea is to compute the conditional distribution of uncertainty after normal score transformation of the original samples. Under the multi-Gaussian assumption, all marginal and conditional distributions are Gaussian, hence fully defined by their mean and variance. The parameters of the conditional distributions are obtained by simple kriging and can be back-transformed to the original units of the variable of interest. An estimate and any summary of uncertainty can be easily retrieved. The main disadvantage of performing multi-Gaussian kriging is that change of support is not straightforward, that is, calculating uncertainty of block grades. We propose a methodology to overcome this limitation by considering a matrix simulation to generate multiple probability fields. Each probability field is used to draw spatially correlated point values from the point-support conditional distributions, and multiple realizations of the average can be obtained. This permits the calculation of the average over the block and its uncertainty. These blocks may correspond to selective mining units or to volumes from longer production periods relevant for engineering decisions. They can even be disjoint blocks, such as when several faces are mined at the same time. POSTMG, a Fortran program to perform these calculations, is described and a case study is provided.

May 1, 2004

By C. D. Shackelford, J. F. Muñoz, M. Vauclin, P. Rengifo, A. Suazo

The results of a field-scale study involving in situ leaching of copper ore tailings using sulphuric acid as the leaching agent, injection wells to introduce the leaching solution and extraction wells to recover the copper-enriched pregnant leaching solution are presented. The study was performed at an abandoned tailings disposal site using a battery of injection and extraction wells. The medium was characterized through the determinations of physical, chemical, mineralogical, and hydro-dispersive properties based on laboratory and field tests, including a tritium tracer test, a pumping test, particle size analyses, and hydraulic conductivity tests. Numerous horizontal strata with different hydraulic conductivities were identified. A previously developed model was used to simulate the leaching of copper ore tailings. Although the study confirms the feasibility of using in situ leaching for recovery of residual copper from tailings deposits, the efficiency of the technology depends significantly on the medium stratigraphy and hydraulic conductivity.

Jan 1, 2001