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By Trevor Harris, Martin Harris

"This paper evaluates the effect of grind size on the flotation performance of a platinum ore from the UG2 reef of the Bushveld Igneous Complex, in South Africa. The study was conducted on the Mintek Flotation Pilot Plant Facility, located in Johannesburg, and represented a thorough evaluation of the application of the flotation modelling methodology developed jointly by the University of Cape Town and the Julius Kruttschnitt Mineral Research Centre at the University of Queensland through the AMIRA P9 Project. A simulation model of the pilot plant data was successfully implemented, providing a set of circuit modelling parameters that appeared to be both consistent and well correlated to measurable characteristics of the ore and the pilot circuit operating conditions. The findings indicate that the methodology that was used could well provide a useful framework for developing optimisation criteria for industrial flotation circuits in combination with appropriate feed grind size and regrind size targets.INTRODUCTIONIt has long been recognised that the size distribution of an ore is one of the most important factors in the determination of the performance of a flotation process. It therefore follows that the optimisation of a flotation plant cannot be considered without due recognition of the interdependence of this process with the process of comminution. There are numerous qualitative guidelines for the selection of an optimum grind target for a particular operation. Mineralogical analysis can readily provide information on liberation as a function of grind, and the desirable particle size range for optimum mineral flotation is well established in both theory and practice (see for example Trahar, 198 1). For some operations, meeting these two criteria simultaneously is relatively simple. For the majority of operations, such mineralogically “easy” deposits, if they ever existed, have long been exhausted, and the optimum grind represents a highly complex compromise between liberation and overgrinding of both desirable minerals and gangue. This is particularly true for circuits that include regrind stages, where both primary and secondary (and sometime even tertiary) grind targets must be specified. As has been pointed out in a recent paper by Bazin and Hodouin (2001), there is little or no information in the literature to assist plant engineers in the selection of optimum grind targets for complex ore deposits, so current practice is primarily based on rules-of-thumb and experience. This problem is further compounded by the fact that once grind targets have been selected for a particular operation, the assessment and adjustment of these targets based on plant surveys is extremely difficult, time consuming and expensive, and is often not attempted unless the plant significantly underperforms relative to expectation. It is therefore clear that the development of a practical quantitative approach to this problem is a high priority for flotation research and development studies."

Jan 1, 2002

By J. A. Drozdiak

In this paper we examine, through pilot-scale testing, the possibility of operating a circuit comprised of two stages of HPGR comminution, followed by grinding through a horizontal stirred mill. In order to assess whether the novel circuit design could achieve the reduced energy requirements indicated in the literature, two more-established circuits, a cone crusher / ball mill and an HPGR / ball mill, were examined using a combination of testing and flowsheet simulation. The results showed that, based solely on the specific energy requirements for comminution, the HPGR / stirred mill circuit achieved a reduction of 9.2% and 16.7% over the HPGR / ball mill and cone crusher / ball mill circuits, respectively.

Jan 1, 2012

By J. A. Drozdiak, A. Bamber

In this paper we examine, through pilot-scale testing, the possibility of operating a circuit comprised of two stages of HPGR comminution, followed by grinding through a horizontal stirred mill. In order to assess whether the novel circuit design could achieve the reduced energy requirements indicated in the literature, two more-established circuits, a cone crusher / ball mill and an HPGR / ball mill, were examined using a combination of testing and flowsheet simulation. The results showed that, based solely on the specific energy requirements for comminution, the HPGR / stirred mill circuit achieved a reduction of 9.2% and 16.7% over the HPGR / ball mill and cone crusher / ball mill circuits, respectively.

Jan 1, 2012

The construction, commissioning and operation of a continuous pilot-scale selective agglomeration (oil agglomeration) unit are described. This plant has been used to recover fine coal from an effluent stream that is produced by a jig plant which scalps the coal from a New South Wales (Australia) colliery. The reject slurry is extremely fine (66.5% minus 53 um) and has an ash content of approximately 40%. The pilot plant can treat up to 0.3 tonne/h of this slurry, producing average product ashes as low as 9.1% and tailings ashes greater than 80%. The average yield observed was62%, which corresponded to a recovery of coal material of 88%. The operation of this pilot plant yielded data that enabled an economic assessment of this type of processing to be carried out. This study showed that selective agglomeration is an economically viable process for eliminating the substantial losses of coal to tailings ponds and minimizing consequent disposal and environmental problems. A commercial plant has been constructed and commissioned on the basis of the data obtained from this pilot-scale operation.

Jan 1, 1979

By Robert B. Francini

Longwall mining and pipelines have coexisted since longwall mining was introduced into the United States. How the pipeline operator reacts to longwall mining under their line depends on many factors. This paper outlines the process the pipeline operator goes through to determine the appropriate response when their pipeline is being undermined. Typical mitigation procedures are reviewed. Finally, the paper looks at current design practices for new pipelines that are expected to be undermined during their lifetime.

Jan 1, 2011

By V. Rajaram, I. P. Nielsen, H. D. Raymond

The Parachute Creek member of the Green River formation in the Piceance Basin, Colorado, contains vast reserves of oil shale, nahcolite, dawsonite, and other accessory minerals. The dry alkali process of sulfur dioxide removal using nahcolite (naturally occurring sodium bicarbonate) has great potential. A room and pillar mining scheme has been designed to extract a nahcolite zone occurring at a depth of 472 m, from the lease application area of the Yankee Gulch joint venture. Geotechnical parameters affecting mine design will be discussed. A preliminary development plan for mining at the rate of 1000 t/d will be described in detail.

Jan 12, 1979

By V. Rajaram, I. P. Nielsen, H. D. Raymond

The Parachute Creek member of the Green River formation in the Piceance Basin, Colorado, contains vast reserves of oil shale, nahcolite, dawsonite, and other accessory minerals. The dry alkali process of sulfur dioxide removal using nahcolite (naturally occurring sodium bicarbonate) has great potential A room and pillar mining scheme has been designed to extract a nahcolite zone occurring at a depth of 472 m, from the lease application area of the Yankee Gulch joint venture. Geotechnical parameters affecting mine design will be discussed. A preliminary development plan for mining at the rate of 1000 t/d will be described in detail.

Jan 1, 1980

By John C. Edwards, Robert C. Bates

Modeling uranium mine radiation control methods and natural environmental radon variations is an extremely complex endeavor. A number of authors have examined particular facets of the problem and have proposed models for their area of interest. Bureau of Mines personnel brought together many of these individual studies, and from them have attempted to develop a coordinated plan for modeling radon daughter concentrations in the uranium mine environment. This approach is described.

Jan 1, 1981

By W. H. Geis

THE following pages summarize the causes that led to the suggestion of unit operation of the Paloma field, the organization of committees, preparation of the Paloma Operators Agreement and the reasons for rejection of the plan.

Jan 1, 1942

By D. G. Hulbert, J. H. Schubert, R. G. D. Henning

"Froth depth, along with reagent addition and aeration rate, is one of the crucial factors that can be used to control a flotation circuit. Sub-optimal setpoints and disruptions in levels have a severe adverse influence on grades and recoveries. A novel control strategy has been developed which provides exceptionally tight regulation of pulp levels. The controller observes and acts on all the flotation levels simultaneously. This provides a clear improvement over the standard approach, which is to use a set of Pl controllers. The system has been run on several industrial plants and has resulted in reduced fluctuations in level; fast responses to setpoint changes, and fast settling times after start-ups or disturbances. Testwork has shown that the improvements in level stabilisation translate into improvements in recovery and grades.IntroductionProcess control and optimization have an important influence on the economic efficiency of flotation plants. Inefficient operation can allow the wrong balance between grades and recoveries, and can also lead to adverse shifts in the grade-recovery relationship. Of all metallurgical operations, flotation loses the largest proportion of valuable material. Better operation can reduce these losses.An essential requirement of a good controller is that it should be able to stabilize and regulate the plant. Stable operation allows the performance of the plant to be observed without being obscured by the effects of disturbances and fluctuations. The optimum conditions can then be detected more easily. Good regulation can maintain operation at the optimum with proper neutralization of disturbances. Only when good stabilization and regulation are achieved can an optimizing strategy be properly applied.Froth depth, aeration rate and reagent addition are the three means by which a flotation plant is generally controlled. These control actions are effective on different time scales. Reagent addition is slower in its effect as some conditioning time is required. Since reagents are only added at the head of the circuit and at a few selected points within the banks, time is required for the effect of reagent changes to move through the circuit. Because of this slower time constant, reagent addition is more suited to process optimization and to dealing with slower changes in the process. An example of these slower changes is variation in the feed."

Jan 1, 1995

By Patrick R. Taylor

A non-transferred arc thermal plasma assisted cyclone reactor has been designed, built and operated to evaluate its use in vitrification of wastes. Simulated waste (liquid, slurry or fine particulate) is injected near the plasma flame, where nearly instantaneous dehydration and calcination reactions happen. A non-transferred arc plasma torch was attached tangentially to the cyclone and is utilized as both an enthalpy source and to provide the gas velocities required to generate the cyclonic gas flow patterns. The closed top cyclone flow sends the solid particulates to the wall, where they are captured by a thin film of molten glass that is injected as a powder at a position lower in the reactor. The molten glass is then collected in a crucible. The feasibility of simulant injection directly into the flame zone and its effect on electrode lifetimes has been studied. Several candidate refractory systems have been evaluated for their suitability for extended use under the demanding conditions present in the cyclone reactor.

Jan 1, 2002

By C. Chapman, P. Cowx

"INTRODUCTIONTetronics Research and Development Co. Limited has installed several plasma torches for steel heating in continuous caster tundishes. An extensive demonstration program on a 14 tonne tundish reported the following advantages of plasma heating.• close control of steel temperature to ± 5°C;• a reduction of the furnace tapping temperature of up to 20ºC, leading to savings in energy and refractories costs ;• improvement in steel quality, to produce a slab product with an equi-axed crystal structure and a reduced number of large sub-surface slag inclusions;• the virtual elimination of oxygen pickup in the tundish; and• the capability of making ferroalloy trim additions to the tundish to permit a change of steel grade during casting, greatly decreasing inventory costs.The Need for Tundish HeatingIn the continuous casting of steel, the function of the tundish is to transfer the molten metal between the ladle to one or more continuously fed casting moulds. Figure I shows a typical temperature profile of molten steel in the tundish over the first cast cycle. It is observed that a rapid drop in temperature occurs both at the start of the cast, due to the tundish refractories absorbing heat, and also during ladle changeover. In addition, as a result of thermal losses through the ladle sidewalls, there is a gradual decline in the bulk steel temperature over the entire heat cycle. Consequently, in normal tundish operation, it is necessary to cast with a high superheat (25°C to 30°C + above steel liquidus temperature) in order to prevent freeze-up of the strand. Problems of high temperature variation and the potential of the steel solidifying in the tundish are greater for small caster units of low thermal mass . A high steel superheat increases the steelmaking vessel process time and refractory wear and prevents the formation of a uniform equi-axed solidification structure in the cast steel, resulting in centre line segregation and porosity. The large drop in the casting temperature that occurs during unsteady state operation causes an increase in the number of sub-surface inclusions, reducing the value of the product. Accordingly, plasma heating may be employed to maintain the molten steel at an optimum temperature to produce a slab of consistent quality."

Jan 1, 1989

By S J. Schafrik, Z Agioutantis, E C. Jong, K Luxbacher

Real-time monitoring of mine operating parameters is available at most mines. However, access to these data for an individual operation is typically underutilised by mine managers and technical personnel. Such monitoring systems are typically designed to provide data streams and alarms to a responsible person, but they are not utilised to extract underlying trends or correlate different data groups. Furthermore, multiple monitoring systems are usually implemented at a given site without interconnection between vendors’ systems or connection to any central management, and mine personnel are only exposed to a minimal subset of such data. Thus, it is not easy to analyse and correlate individual data streams and generate information to enhance day-to-day operational decision-making and improve safety and efficiency.This paper addresses the primary challenges associated with centralising data management and effecting greater utilisation of the vast amount of collected data, while at the same time reducing the time and effort required to manage such large data sets. Furthermore, it presents the conceptual design of a database application that can organise, present and analyse data collected by multiple sensors in different environments. The database is designed to operate in a passive manner so that active mine data management systems are not impacted. An example is given where this database is used for managing atmospheric data collected at an underground coalmine operation in the US. These techniques have a universal application and can be incorporated in a wide range of mining and construction projects.CITATION:Agioutantis, Z, Schafrik, S J, Jong, E C, Luxbacher, K and Karmis, M, 2015. A platform for managing and analysing atmospheric data in underground coalmines, in Proceedings Third International Future Mining Conference, pp 3–10 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By KENNETH W. GREENAWALT, William Greenawalt

THE patent system, through which an inventor is given exclusive right to his invention for a limited period as a reward for his industry and in reimbursement of his expenditures, originated in England in the famous "Statute of Monopolies," enacted in 1623. The first patent granted in America was to Samuel Winslow, in Massachusetts, in 1641. The basis of the patent system of the United States is a provision in the Constitution giving Congress the power to secure to inventors for a limited time the exclusive use of their discoveries. The first legislative enactment was the law of 1790, which was placed on the statute book after Washington had addressed Congress in its favor. Under this law, the Secretary of State, the Secretary of War, and the Attorney General constituted the board for the examination of patent applications and the granting of patents. The first Secretary of State, Thomas Jefferson, became the first administrator of the patent sys- tem in this country. He personally examined every application filed during his term of office.

Jan 1, 1930

By Dean Goodermote, Carla S. Stone

I Introduction Coal fuels China. Roughly 70 percent of all commercial energy demand is supplied by domestic coal production and with the recent Chinese opening to the West, the Chinese Coal Industry may figure prominently in the export market as well. Because of the importance of China's coal industry to the future of China and the Pacific Rim energy balance, this paper reviews the industry and offers some cautious projections for its outlook. II Energy's Position in the Current Political and Economic Climate Traditionally, Chinese society has been dominated by the policies of its most important government leaders. Deng Xiaoping, Vice Chairman of the Communist Party is the current leader of China. Deng and his proteges are pragmatists. Although China's government structure is based on Marxist/Leninist tradition, Deng and his followers are promoting experiments with market economics and expanded relationships with Western Countries, which have encouraged foreign investment in China. Energy companies represent just one type of industry that is interested in helping the Chinese to develop their abundant natural resources. Although China's leadership is committed to a program of economic modernization, that program currently is experiencing what the Chinese government terms "readjustment". Readjustment cuts back in imports due to deficient foreign exchange and deemphasizes heavy industry, while it encourages agricultural and consumer goods output and, most imporant, energy production. Increased Chinese coal and oil production is essential both to fuel industry and, equally important, to provide foreign exchange. If sufficient energy production is not forthcoming, then economic growth will be severely retarded. China's 1979 per capita GNP of $260 is only slightly better than the weighted average achieved by low income countries of $230. (1) Delays in growth could lead to social unrest, threatening the position of the current leadership. Since there is no institutionalized mechanism for leadership succession and policy continuation, it is reasonable to assume that leadership changes could result in energy policy changes. III Energy Consumption Energy production is important to China's future economic health as highlighted by the World Bank. If China's economy grows rapidly, 5 percent to 6 percent during this decade, the Bank noted, a significant energy shortfall could occur as early as 1985. This state of affairs contrasts sharply with China's current position as a net hydrocarbon exporter. (2) To assure a healthy economic future, China's leadership is attempting to reduce its rate of increase in energy demand through conservation as well as to boost energy output. A massive conservation promotion program has been underway since 1979 and there is much room for improvement. China's industrial sector is only about half as energy efficient as is U.S. industry. (3) During the last two decades, each percent of increase in GNP has been accompanied by a 1.8 percent of increase in energy consumption. (4) This compares rather poorly with the United States where a less than one-to-one relationship exists. IV Energy Supply The short term prospects for oil production are uncertain. Production increases were rapid in the 1960's and early 1970's, averaging 20 percent annually, but most of this increase came from one field, Daquing. Now that Daquing's production has peaked and the offshore potential has yet to be developed, petroleum production has maintained a plateau of 2.1 million b/d, at least temporarily, of which approximately 15 percent is exported. (5) Output

Jan 1, 1982

A method, based on the macroscopic population balance equation allowing the dynamic simulation of a multistage adsorption plant given an arbitrary rate expression, is described. The partial differential equations resulting from this method are simplified using the method of characteristics. The simplified equations can then be solved using standard ODE integration techniques. The procedure is illustrated by means of data typical of a CIP application. Requirements for data structures which allow the incorporation of the carbon-in-pulp (CIP) model (and other unit models) into a general metallurgical simulator are described. Based on these considerations, it is concluded that more generality in the description of distributed quantities such as loading and particle size is provided by the use of mass density at fixed class boundaries, rather than discrete masses within fixed classes as has hitherto been used by ore-dressing simulators.

Jan 1, 1987

In the early stages of opening up a mine, when there is some uncertainty as to its future career, necessitating caution in laying out works of a permanent character, the want is often felt of an assay furnace, easily built and easy of transportation, should the" mine " prove to be " no mine." Again, cases occur in which parties buy the right to treat comparatively small heaps of tailings, and then shift their plant to other localities. Under these circumstances it is necessary to restrict the plant to the barest necessaries, to suit, so to speak, the nomadic character of the work.An assay furnace that is really portable, easily transported, erected, taken down, of little weight, always ready for action on short notice, is indeed in these cases a desideratum which has long been wished for. The gasoline furnaces introduced intothe Australian market some time since practically fulfil these conditions; but they have the fatal drawback of being dependent on a constant supply of the liquid fuel, gasoline, which is seldom, if ever, obtainable locally in' any wayback mining township...

Jan 1, 1904

By S. K. Bradford

(Pittsburg Meeting, March, 1910.) FOR years past I have traveled in quest of promising mining-properties, over almost impassable mountain-trails to remote places in the mining-regions, usually, many miles from an assay-office. If, upon examination, the formation and the ore-deposit appeared favorable, a quick determination of the value of my samples was necessary, in order that I might take intelligent action with reference to the acquisition of the property. A journey with my samples to civilized regions often meant weeks of delay, and perhaps loss of opportunity. How many, under similar circumstances, have returned with their assay-results from such a journey, only to find that some audacious speculator had " optioned" the property ! True, a first payment could have been made and the chances taken on the results; but experience has taught that rich-looking ore is not of necessity valuable. Personally, I would not hazard a ten-dollar bill on any property without first determining by assay the value of the ore. To carry the usual complete assay-paraphernalia over such mountain-trails was impracticable by reason of the loss of time involved, the great expense of transportation (charged according to weight), and the fact that a few such trips would almost certainly wreck the outfit. For these reasons I began a process of elimination and substitution which finally enabled me to carry, in an ordinary 26-in. valise, sufficient apparatus and supplies for, say, 100 assays of adequate commercial accuracy. My final outfit was as follows: APPARATUS. Small hammer; steel mortar (2.5 in. wide, 3 in. high, with stand sawed off flat, so that it can be used as an anvil and for

Jan 1, 1911

By P. Lopez, E. Wellman, N. Risso, A. Anani

Current machine learning models used for roof fall hazard prediction are mounted on expensive sensors, computationally expensive, or lack the robustness for accurate prediction in the underground mining environment. This research aims to provide a design methodology for a robust, low-cost, deep learning-based algorithm for underground mine roof fall hazard prediction. A data sampling plan is developed to ensure the replicability and robustness of the developed model. In addition, feature engineering and transformation methods are described to identify relevant features for hazard identification. The methodology described here will be used in model development, tested, and implemented as a real-time mobile device application. The new tool will be expected to detect roof fall hazards in real-time and contribute to a crowdsourcing approach for underground hazard detection.

Feb 1, 2023

By B. Sameti

Blast engineers have been taking advantage of image-based rock fragmentation analysis methods for the past 3 decades to estimate rock size distributions. These methods utilize a wide range of image segmentation techniques, from manual to fully-automated, to delineate the edges of rocks in images. Rock delineation results are then converted to physical rock sizes (and percentage passing curves) by scaling the image pixels to correspond to physical measurements. The size scaling process is critical for acquiring physical measurements, but specific to the limitations of different applications. This article starts by presenting a shovel bucket-based fragmentation analysis system, where scaling is done using the known width of the shovel bucket within the image. Next, it describes methods that use pictures captured by digital cameras with scaling reference objects in the view. Finally, the article presents a method that uses three-dimensional imaging to capture images without the need for scaling reference objects. A portable device which utilizes a three-dimensional imaging method is proposed, and compared with the other methods. The proposed solution combines the generated three-dimensional points with the delineated rock boundaries in the image to reconstruct the surface, and generate accurate rock size estimates and percentage passing rock size distributions. System operation is described and its accuracy and performance are discussed for various scenarios. It is shown that since the device does not require a physical object for scaling reference, it is free from the limitations of other methods, and can be applied for automatic rock size measurement from various sources such as mining shovels, loaders, crushers, stockpiles, haul truck beds, and conveyor belts.

Feb 23, 2014