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By Emma Arakelova

?2?2 (98 %) vapour passed through a reactor at 25Pa where a Zn? target was placed at 273K- 373?. Experiments were carried out on a flow- type vacuum device. ?2?2 decomposition on Zn? surface accompanied by formation of a Zn-containing volatile complex which transferred to the gas phase, and Zn? deposited on a substrate at condensation. As the substrate, five sequentially located quartz cylinders were used at 293K- 423 K (?n). Decomposition of the Zn-containing complex on quartz substrates carried out as a first- order reaction. ?The complex decomposition constant (??) increased with the substrate temperature (?n=293 K, ??=7.05 sec-1;?n = 373 K, ?? = 87 sec-1;?n = 423 K, ?? =158 sec-1). ?The complex decomposition constant did not practically vary when the target temperature increased; the complex formation rate increased slightly.

Jan 1, 2006

By Mike Sapiro

"Heath Steele Mines is a base metal producer situated near Newcastle, N.B. presently treating 3500 TPD of complex Cu-Pb-Zn ore. The ore consists of massive fine grained sulfides averaging I. 1% Cu, 1.6% Pb and 4.5% Zn.The original mill started in 1956 at 750 TPD and was successively expanded through 1500 to 3000 TPD in 1969. In 1972 an expansion to 4000 TPD was initiated. It was planned to obtain the maximum benefit from equipment and manpower by adding some process equipment, instrumentation, an on stream analyser, and a process control system. The benefits from this approach could be greater than normally expected, because of the complex metallurgy of this ore.IntroductionThe crushing plant is of conventional design with two 5 ½ ft, Symons cone crushers with the crushed ore screened to -7/8 inch on a 61 x 16 1 Al I is Chalmers vibrating screen and stored in four 1000 Ion bins. There are two para I lei grinding circuits, each one consisting of the following: one Rod Mill in open circuit, one Ball Mill in closed circuit with two 20"" Krebs cyclones, and one Ball Mill in closed circuit with three 15"" Krebs cyclones, Al I the Mills are 9' x 121 Al I is Chalmers Mills. The secondary cyclone overflow from each grinding circuit is thickened and combined to form flotation feed. The final product is 65% - 400 Mesh. Two regrind mills have been installed as part of the expansion."

Jan 1, 1977

By William Stewart

Recitations were taking place in the red schoolhouse at Orneville, Maine. It was winter and the snow lay deep on the ground, but some of the scholars were in bare feet, and only half as many hats hung on the pegs as there were potential wearers in the seats. That was forty years ago; and the pioneers of northern New England were more noted for their industry than for their possession of the fruits of it.

Jan 1, 2007

The New Zealand Steel Ironsand Slurry Pipeline was successfully commissioned in February 1986. The project includes 18 km of high pressure, polyurethane lined buried pipe. McConnell Dowell Constructors Limited has developed a coupling which has allowed this pipeline to be fully welded. The design and development of the coupling and its application on this project is discussed.

Jan 1, 1986

By Gerrit V. R. Goodman

In This Chapter [Design and operation of machine-mounted scrubbers Dust control with scrubbers and blowing ventilation Dust control with scrubbers and exhaust ventilation Dust control with exhaust ventilation and no scrubber Dust control methods common to all continuous miner sections Dust control for roof bolters] This chapter explains how to control dust at continuous miner sections in coal mines where the main dust sources are continuous miners and roof bolters. In relation to dust, there are three categories of continuous miner faces depending on the type of ventilation and whether or not a machine-mounted dust scrubber is used. These are— 1. Mining machines with dust scrubbers used with blowing face ventilation 2. Mining machines with dust scrubbers used with exhaust face ventilation 3. Mining machines without scrubbers used with exhaust face ventilation The approach to dust control is somewhat different in all three of these. However, there are many dust control features (such as the need to provide adequate airflow) common to all continuous miner sections. For workers at roof bolter faces, there are two dust sources: 1. Dust from the continuous miner when it is upwind. 2. A malfunctioning dust collector on the bolter, which allows dust to escape DESIGN AND OPERATION OF MACHINE-MOUNTED SCRUBBERS [Almost all new continuous miners are equipped with scrubbers. When the dust is excessive, it is possible that the scrubber needs some maintenance.]

Jan 6, 2003

By D. Gearhart

Full-scale tests are conducted on mine roof supports using protocols developed by the National Institute for Occupational Safety and Health (NIOSH) using the unique capabilities of the Mine Roof Simulator (MRS). These protocols simulate the loading conditions that the support will be exposed to in an underground mine to determine the performance capabilities and limitations of the support. Some tests are conducted with rigid boundary conditions, creating uniform contact and near ideal axial loading conditions. These tests are used to determine the ultimate performance potential of a support, including the strength, stiffness, and stability. For prop supports where stability is a critical design issue, tests are implemented to induce buckling by a modified end condition, eccentric contact, or biaxial loading. It is important to determine the cpacity of the support design when the support is subjected to unpredictable loading conditions. This paper examines the effect of end conditions and load profiles on prop support performance and applies a new analysis methodology based on eccentric loading to determine a factor of safety for load capacity. Recommendations for installation practices that minimize eccentricity and therefore preserve capacity are also provided.

By Pedro Jorge Walburga Keglevich de Buzin

O cloro no processo de aciaria elétrica tem sua principal fonte nas contaminações de origem orgânica existentes nas matérias-primas usualmente empregadas, principalmente na sucata. Apesar dos atuais níveis de cloro não perturbarem a fabricação do aço nas mini-mills, a presença deste elemento e dos compostos por ele gerados tem influência deletéria nos aspectos laborais, ambientais, de manutenção das instalações e na reciclagem das poeiras de aciaria. Neste trabalho, com base na integração de dados da literatura, da indústria e de propriedades físicas, químicas e termodinâmicas das substâncias envolvidas é feita uma avaliação qualitativa da passagem do cloro na aciaria elétrica e sua distribuição nas diversas correntes de massa de saída do processo. Foi concluído que a maior parte do cloro que entra no FEA deixa o sistema concentrando-se nas emissões do processo, principalmente nas poeiras de aciaria, sob a forma de cloretos alcalinos.

Oct 30, 2017

By Taner Sumer, H Altay Guvenir

Fragmentation in rock quarries is tried to be achieved by changing the specific charge, drill pattern and bore hole diameters by different experts. This paper is a brief summary consisting of the utilization of practical experiences of the other group on cost optimization procedure that takes into account blasting, transportation and crushing as a whole process and optimize the cost by defining the optimum gelatin based explosives to be used as a main primer of anfo in three different limestone and granite quarries, with similar rock characteristics.

Jan 1, 1993

By A. Beitz, P. Smartt, G. Einicke, G. Rowan, P. Glynn

Coal is Australia’s highest export earner and Australia is the world’s largest exporter of coal. With coal now being extracted from deeper reserves under increased risk profile, and in the interest of aiding the stability of coal supplies, Japan is funding a number of safety projects in Australia and China. The CSIRO, Australia’s premiere research organisation with the country’s largest exploration and mining research group, are currently undertaking a jointly funded Japan-Australia safety project at Anglo Coal’s new Grasstree Colliery in central Queensland. The project, entitled Mine Communication and Information for Real-time Risk Analysis, will deliver step-change capabilities in data integration, decision support, gas monitoring, geo-technical monitoring, emergency response and personnel safety to the Grasstree Colliery. Some key activities include: developing and installing underground coal mine Ethernet LAN components, real-time monitoring of gas and geo-technical sensors, MODBUS serial to TCP/IP converters, e-reporting of underground conditions, emergency guidance systems and underground trials of Internet Protocol telephone and video. The project seeks to integrate (in real time) key data sets from the comprehensive and diversified range of propriety system currently in use at mines (ventilation, strata, operations e.g. haulage, pumps, conveyors etc) into a single integrated risk management interface. This interface will filter the data through a rules-based inference engine that will cross reference the various data streams, compare with past events and outcomes associated with the similar historical data and present this “intelligence” to

Jan 1, 2003

High Pressure Sulfuric Acid/Oxygen Leaching of Platinum Group Metals Bearing Ni-Cu Mattes The processing of platinum bearing Ni-Cu ores for the extraction of platinum group metals (PGMs) involves comminution, flotation, smelting, and converter treatment of the furnace matte. Leaching circuits are predominantly used for further processing to separate the base metals and PGMs contained in the converter matte. Nickel dissolution is primarily achieved in the first stage leach (high pressure or atmospheric leaching, or a combination of the two), which is followed by second stage high pressure sulphuric acid/oxygen leaching to dissolve copper and the remaining nickel. PGMs are recovered from the leaching residue in downstream processes, and their dissolution in the first two leaching stages must hence be limited. Studies have been conducted to investigate the leaching mechanisms and kinetics of base metals in different leaching environments. The key operating parameters that influence the leaching kinetics of these metals include the temperature, acid concentration, degree of agitation, feed particle size distribution, and oxygen partial pressure. There is, however, a limited understanding of the behaviour of PGMs in the high pressure leaching process. Consequently, this process is controlled based on operators' intuition despite its importance in the recovery of PGMs. An improved fundamental understanding of the behaviour of PGMs in this leaching environment is required to be able to accurately model the process. This in turn will allow the development of an improved control strategy and the estimation of optimum operating conditions. An overview of the leaching mechanisms of base metals and the effects of key operating parameters on their dissolution kinetics in different leaching environments are presented. Models that have been developed to predict the leaching behaviour of base metals are discussed and evaluated. Finally, initial results obtained with an experimental setup that will be used to investigate the behaviour of PGMs in high pressure leaching systems are discussed and compared with published results.

Sep 13, 2010

By Edward W. Parsons

The transverse force developed by expansion-shell rock-bolt anchors on the wall of a drill hole as the bolt is tensioned was measured by the Bureau of Mines using a device specially designed and fabricated for attachment to a universal testing machine. Load cells equipped with electrical-resistance strain gages provided the data from which the transverse force, in pounds, was calculated. Seven different expansion-shell anchors were tested, and the ratio of transverse force to bolt-tension load was found to range between 0.98 and 1.94 to 1.0. The drag load appeared to be the major cause of the transverse-force variation, but the relative effects of individual factors that affected the ratio between the transverse force and the bolt tension were not determined.

Jan 1, 1968

By David H. Tang

Massive pillar failures were observed at two underground coal mines. The results of stability analysis using traditional pillar design formulae did not agree with the underground observations. Finite element models were used to analyze the causes and mechanisms of the pillar failures. The results were confirmed by the underground observations. Finally, the improved mine plan for each case was derived to ensure the stability of the underground structure.

Jan 1, 1990

By F. F. Aplan

Pollution control will be of utmost importance in the 1970's. In this area, the mineral process engineer has a special competence to understand and remedy many pollution situations. There is an old adage that goes, "Build a better mouse- trap and the world will beat a path to your door." Would that it were so, but the reality of the situation is such that, just as a supplier must sell his machine, a professional man must sell his competence. It is a sad but true fact that mineral processing engineers have not done a very good job in selling their extensive competence in the control of a broad range of pollution problems. Recently one of our students visited a paper pulp mill where he was shown a foam fractionator used to remove paper pulp fibers from plant discharge waters. "Foam fractionator hell, that's a flotation cell!'' was his comment. Ah so, it would appear that large numbers of technical people consider themselves experts on "foam fractionation" Or is it that we have been very remiss in demonstrating the usefulness of our equipment and processes and our professional competence to solve, these pollution problems?

Jan 1, 1970

By R. O. Burt

"Gravity Concentration, the oldest form of Mineral Processing, remains of major importance to the Industry. Current applications of Gravity Concentration are briefly examined.The Paper details one approach to the development of a Gravity Concentration Plant, from laboratory and mineralogical techniques, through Pilot Plant testing, where applicable, to the actual design of the plant.INTRODUCTIONGravity Concentration, once the major method of concentrating minerals has, for much of the twentieth century been regarded, like the dodo bird, as obsolete. However, in more recent years it is enjoying something of a renaissance, and is once again being treated as a useful, economic alternative in the Mineral Processing Engineers' arsenal.An indication of the broad application of gravity concentration is the variety of minerals presently recovered. A list is given in Table 1; this list is not exhaustive."

Jan 1, 1984

By G. M. Hughes, J. Ellis

"IntroductionHydraulics has been considered a science for thousands of years. Applications included water wheels, dam; and slice gates but today the term ""hydraulics"" commonly refers to ""power hydraulics"" in which fluid is used under controlled pressure to do work. The mining industry employee’s hydraulics in practically every aspect of its operations, on such equipment as trucks, front end loaders, LHD units, crushers and hydrostroke feeders. The many benefits of hydraulic drives such as ease of variable speed control, high power: weight ratio low envelope size of hydraulic actuators and ease of maintenance have been extensively developed in the pulp and paper, chemical, steel, and other basic industries, but until quite recently, concentrator operators have not taken advantage of the versatile methods of power transmission offered by hydraulic systems.After some preliminary testing at the Lynn Lake concentrator Sherritt Cordon Mines Limited installed several hydraulic system; at their Fox Mine concentrator to drive slurry pumps and conveyors. The systems used at Fox and the systems which will be installed at the Ruttan concentrator are briefly described in this paper. Since acceptance is based mainly on understanding a few basic principles of hydraulics system; including pumps, motors, circuitry and central methods are also presented in the paper.PRINCIPLES OF POWER HYDRAULICSBasicsHydraulic systems provide an uncomplicated, versatile means of power transmission. The basic system is quite simple. It consists of five main elements, as shown in Figure 1, which are:1. Prime Mover - generally an electric motor.2. Hydraulic Pump - fixed or variable positive displacement type such as a piston or vane p.mp which displaces a constant amount of fluid for ead1 revolution - this unit converts mechanical energy of the prime mover into fluid energy.3. Oil Reservoir - a standard tank to operate under atmospheric pressure which has a capacity of 2 - 3 times the maximum gpm outp.it of the hydraulic pump."

Jan 1, 1972

By Severino Albani Junior

A Gestão de Ativos vem ganhando espaço no contexto industrial ano após ano principalmente após 2014, quando ocorreu o lançamento da ABNT NBR ISO 55000. Dentro desse contexto, o tema Manutenção e principalmente a Confiabilidade foram explorados pela ArcelorMittal Flat Carbon South America com o lançamento em 2013 do Plano Diretor de Manutenção e Gestão de Ativos. Este trabalho visa mostrar as etapas seguidas na aplicação de técnicas de Engenharia de Confiabilidade, os atores necessários para a realização do trabalho e os resultados positivos alcançados. Dentre os resultados está a definição da estratégia da manutenção focando a manutenção baseada em condição, possibilitando a otimização dos recursos envolvidos e influenciando positivamente na redução da taxa de falhas da Máquina de Lingotamento Contínuo 01 da ArcelorMittal Tubarão. Estes resultados também levam a expressivos ganhos financeiros, além de melhora da previsibilidade operacional.

Oct 30, 2017

By M. Buxton

Sensor derived data can add value across the mining operating chain ranging from resource definition, extraction, pre ? concentration, mineral process monitoring and assessment of product quality. Most documented studies on the use of sensors in mining focus on specific technologies for specific applications. These studies do not take into account different aims, objectives and operating conditions at different steps in the value chain. The first part of this contribution assesses key physical performance and discriminatory requirements of sensors applied in each portion of the mining value chain. The second part proposes a framework of methods for quantifying the value added by additional sensor information. Integrating the sensor based technology and the economic value quantification allows for both, designing an economically optimal sensor monitoring network along the whole mining value chain and optimizing efficiencies. Illustrative studies demonstrate the significant economic benefits, in particular in reduction of exploration expenditures, increase in extraction efficiencies, increase in ore product quality and improvement of processing efficiencies.

Feb 27, 2013

By Jeff Kravitz, John Kovac, Wayne Duerr

Since 198 1, Federal mining law has required every miner working in underground coal mines to have a self-contained, self-rescuer (SCSR) available for use in emergencies. Some miners that have escaped from fires using SCSR's have reported that they had to remove their mouthpiece to talk during escape, thus compromising the protection afforded by the SCSR. If miners are in thick smoke during an escape, they may have trouble if they become separated from their group. The visibility can be so poor that separation can occur at very short distances. To address this problem, two-way, FM radios were built into the SCSR to improve the ability to communicate should the miners be separated over relatively short distances. The SCSR prototypes built and used in testing included both two-way radios and improved mouthpieces. Comparison studies were conducted using combinations of the new and old mouthpieces, and trials using the radio or not using the radio. Subjective judgments indicate that communication ability was significantly improved using the prototype devices. Communication problems have been encountered with teams using standard voice- powered communications systems. Mine rescue teams perform rescue and recovery work under extremely hazardous conditions, life lines are a standard part of mine rescue team equipment. Leaky feeder and quasi-leaky feeder life line communications systems provide significant improvements over standard systems. These improved systems allow all members of the team to communicate with each other and their base of operations. These innovations will significantly enhance the safety of mine rescue operations.

By R. Patrick

As a unique South African organisation, CSIR: Division of Mining Technology (Miningtek) strives to support the mining industry by improving health, safety and productivity through developing, adapting and transferring technology. Considerable effort is currently directed towards the development of potential non-explosive mining methods with the potential to allow continuous mining in narrow reef conditions. Besides improving productivity, continuous mining results in concentrated mining which has a significant impact on reducing infrastructural costs. Impact Ripping and Water Pulse Rock Breaking have been tried on gold mines, whereas Activation, Mini-Disc? cutting and the Plasma Holemaker are currently being tested on platinum mines. The organisation?s many years of experience in novel rockbreaking, together with its world-wide collaborator network, has placed it in a unique position to assist the mining industry and manufacturers in developing and/or adapting existing technologies for application underground. Currently a range of technologies are being investigated, which have reached different stages of maturity. The main technologies under investigation are; - Impact ripper system - Water pulse rock breaking - Activated undercutting rollers - Mini disc cutters - Electric rock breaking

Oct 1, 2001

By R. B. Throndycraft

"1. Belt-Drop Agglomeration Preferred at Heap Leach Operations. The agglomeration method now preferred at heap leach operations utilizes belt-drops along conveyors. Belt-drop agglomeration is being designed into numerous upcoming heap leach operations. It offers substantial capital cost savings over previously favored drum agglomerators. It has such significant operating and maintenance advantages that some drum agglomerators have been retired in favor of belt-drops.The majority of heap leach operations are now built with crushing included in the flowsheet. If crushing is included, belt-drop agglomeration can be added for almost no cost. The agglomeration equipment is simply a few conveyor transfers, designed to provide the tumbling and rolling action which forms the agglomerates. Controlled water sprays are needed at each of these agglomeration transfers. Cement or lime is added as a binder, to stabilize the agglomerates. This reagent is also needed to raise pH to safe operating levels.Addition of the pH control reagent before stacking the ore offers a reagent cost benefit. In the belt-drop mixing technique, the ore is intimately mixed with the lime (or cement). After stacking on the heaps, when the cyanide solution is sprayed onto the high-ph ore, very little cyanide is consumed. Without the pre-addition of lime or cement, the leach solution is sprayed onto neutral ore. The mixture of high-pH leach solution and neutral pH ore causes the solution pH to drop, releasing cyanide gas. This release is minor from a safety viewpoint, much less than dangerous, but the gas release is a costly waste of the cyanide reagent. Pilot-scale comparison tests were made at Pinson. Ore pre-treated with lime or cement showed 30% less cyanide consumption than untreated ore."

Jan 1, 1989