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By A. Musschoot

"The paper will review general types and designs of vibratory feeders, describing briefly the design features and characteristics that apply to the application of specific types. Control considerations for selecting types will be dis• cussed, such as fixed or adjustable, manual or automatic, individual or multiple bank, and process requirements. Design parameters for hopper openings and installation geometry will be discussed, including consideration of material size distribution, segregation, moisture content and other characteristics, based on practical applications and experience as well as theory. Pan designs and the selection of pan materials will also be discussed with reference to wear, corrosion, impact and practical economic factors."

Jan 1, 1972

By Patrick Sullivan

Over the past few years, successful operations for processing phosphates employing the Grate-Kiln System have been achieved. Control and instrumentation philosophy followed in these installations are described and analyzed. Concepts utilizing digital techniques and computer systems appropriate for similar installations are also discussed.

Jan 1, 1967

By Alberto Pacheco Pacheco

En el presente texto se analiza el fundamento de lógica fuzzy aplicada al control de molienda de minerales, la que nos permite simular el comportamiento humano en la operación molienda, con la que se plantea el algoritmo de control inteligente de molienda.

Sep 12, 2005

By Jacques LeBel

After a brief definition of asbestos and a review of regulations, the elements of asbestos dust control are outlined for various asbestos manufacturing industries. To prevent the asbestos dust to become airborne, the general procedure is to control the dust at the source by enclosure and exhaustion. The asbestos dust is collected and removed from the air with bag filter collectors of high efficiency (better than 99%) to ensure that the air emitted to the general environment or returned to the workplace are below the existing asbestos emissions regulations. Dust control systems should be regularly inspected and serviced to maintain at all times the efficiency and reliability of the equipment. Other effective procedures for asbestos dust control are also considered.

Jan 1, 1984

By Song Guo

This paper will present the roof bolting finite element model developed at Jennmat Corporation used to study the control mechanism of the tensioned bolt system in the laminated roof with a large horizontal stress. In addition, it will discuss general support concepts pertaining to the tensioned bolt system which are derived 6om a series of studies in conjunction with the authors' working experience and extensive research efforts over the years.

Jan 1, 1997

By Sergio Quiñones

El presente trabajo señala el control metalúrgico en la planta concentradora de Toquepala a través de la mineragrafía. La mineralización del cobre se realiza en dos grupos: el diseminado (36%) y relleno de fracturas (64%). La dacita porfirítica presenta la mayor intensidad de diseminación fina. En este sentido, el estudio microscópico cuantitativo actual ha contribuido a conocer mejor la caracterización morfológica de nuestro mineral en las diferentes etapas de la concentración y va desde la alimentación hasta la obtención de concentrados y relaves.

Sep 13, 2001

By Glenn R. J

Treatment processes are outlined for the recovery of rutile and zircon from the heavy mineral-bearing sands on the east coast of Australia. With the exhaustion of the higher grade deposits and the imposition of more rigid specifications for the finished products, strict metallurgical control has become necessary.A description is given of the methods used by The Titanium Alloy Manufacturing Co. Pty. Limited to control the operation of suction dredging, of wet concentration using fans and spirals, and of dry separation using high tension and electromagnetic processes. By applying these methods a plant designed for an output of 15,000 tons of rutile per year has been tuned to produce over 20,000 tons of rutile and a corresponding amount of zircon.Details are given of (a) the method of drilling to determine the extent and grade of the ore bodies, (b) a simple electrically-timed pneumatic automatic sampler, and (c) the methods developed for the physical estimation of quartz, rutile, zircon, ilmenite and "others" in the products of plant operation.The method used for calculating the metallurgical balance and the forms used for the reporting of production results are presented.Examples are given which show the value of this detailed production and metallurgical control of plant operation.INTRODUCTIONThe organization which is now known as "The Titanium Alloy Manufacturing Co. Pty. Limited" (T.A.M.Co.)-a subsidiary of National Lead Company-commenced operating at Yamba, N.S.W., in 1935. A mixed natural concentrate was at first simply dried and bagged and later was upgraded by the removal of silica and the lighter heavy minerals on shaking tables and, after air-drying, was bagged for export. At that time zircon was the most wanted constituent.

Jan 1, 1960

By S Jackson, I Arbuthnot

The use of High Rate Thickeners has gained wide acceptance in the mineral treatment industries. The design of these units is characterized by an efficient deaeration and flocculation chamber, and introduction of the flocculated feed solids into a preformed floc bed zone. By these means the settling process is accelerated and consequently High Rate Thickeners achieve a significantly higher throughput per unit area than conventional thickeners.   The object of a control system on a High Rate Thickener (HRT), as on a conventional thickener, is to obtain the required underflow density and overflow clarity at all feed conditions. The feed conditions which may vary include volumetric and mass feed rate, pulp density, particle size and particle type. A conventional thickener has a large volume and cross sectional area, and changes in performance occur slowly û the operator has time to observe and react to these changes to maintain control. On a HRT, there is a much reduced residence time and therefore control parameters need to be reset more frequently. Although manual control is possible, the use of automatic control systems is therefore desirable to avoid excessive operator attention, while optimizing control of density and clarity. Automatic control of a conventional thickener is usually achieved by an underflow density loop which regulates the rate of withdrawal of underflow. A turbidity meter is sometimes used to measure overflow clarity and regulate the addition of a coagulant or polymer flocculant. These measures are not adequate on a HRT, because they would not give optimum control and could lead to excessive flocculant use. To achieve optimum operation in a HRT, the floc bed level should be maintained above the feed inlet point in the thickener. This bed level has become the key variable around which most control systems have been designed. However, a number of problems have occurred which has resulted in poor control, or only partial control of thickener performance. We will describe some of these problems, and a solution which is simple and effective.

Jan 1, 1990

By B G. Lottermoser

Phosphate induced stabilisation has been used to create passive iron phosphate coatings on pyrite and pyrrhotite. The formation of solid phosphate coatings on sulfide grains thereby inhibits sulfide oxidation. The aims of the study were to determine whether phosphate induced stabilisation could control sulfide oxidation and metal mobility in partly oxidised, polymineralic, sulfidic mine wastes. Waste materials were obtained from the acid mine drainage generating, abandoned Montalbion silver mine site, far north Queensland, Australia. The waste consists of quartz, kaolinite/illite, sulfide minerals (galena, chalcopyrite, tetrahedrite, sphalerite, pyrite, arsenopyrite), and pre- and post-mining oxidation products (hydrated Fe, Cu, Pb and alkali mineral salts). SEM observations of waste material treated with potassium orthophosphate showed that metal, metal-alkali and alkali phosphate coatings developed on all sulfides (with the exception of tetrahedrite). The abundance of phosphate phases was dependant on the availability of cations in solution for complexation with the phosphate anion. In turn, the release of cations was dependent on sulfide oxidation or the dissolution of efflorescent mineral salts. Experiments aiming to dissolve these phosphate coatings û using a strongly oxidising solution û showed that the phosphate coatings remained stable, preventing acid generation and metal release. The results of this study demonstrate that liquid phosphate stabilisers can suppress sulfide oxidation and immobilise metals in partly oxidised, polymineralic mine wastes.

Jan 1, 2003

By Kazuhiro Nisizono, Takashi Kuroki, Nobuyuki Mori, Keisaku Ogi

"The improvement of critical current density and mechanical property is essential to the practical application of the superconductive oxides. A solidification technique is developed in this study for the growth of columnar or single Y123 crystal with finely dispersed Y211 and Ag particles through a monotecto-peritectic reaction of Li.(Ba-Cu-Ag-0 rich liquid)+ Y211-+ Y123+Lz(Ag rich liquid). The large solidification rate and temperature gradient can refine the Ag and Y211 particles. But Ag-free region is widely formed along the crystal growth direction in the central part of the Y123 cell. Since this phenomenon occurs because of the cellular growth, it is necessary to narrow Y123 cell width or to grow Y123 crystal with flat freezing interface. By controlling crystal growth direction using a seed crystal, Y123 columnar or single crystal with uniformly dispersed fine Ag particles are obtained. The· behavior of Ag and Y211 particles during the solidification of Y123 crystal is simulated by the peritectic growth model of faceted Y123 crystals.IntroductionY-Ba-Cu-0 superconducting oxide (YBCO) with high critical temperature also has excellent superconducting characteristic under the high magnetic field. The critical current density (Jc) has been enhanced by ·using unidirectional-solidification technique, which can overcome the weak-link problem at grain boundaries and control the crystal orientation and the distribution of Y211 particles which give effective magnetic flux pinning centers in the Yl23 matrix [1-4].In addition to improving superconducting properties, it is necessary to improve mechanical property for the practical application. The silver addition to the melt-textured YBCO superconducting oxide has been reported as the effective method to improve mechanical properties without degrading superconducting properties. Since the material properties are considered to be largely affected by silver particle size, form, dispersion state etc. in the Y123 phase, it is important to control Ag distribution in YBCO/Ag composites. Besides, it is also reported that the silver addition improve the corrosion resistance to the water and CO2 [5,6]. Nishizono et al. [7-9] have reported that the silver distribution in the YBCO/Ag composites is largely affected by the solidification condition, but yet some unclear points are also remained. YBCO has been also fabricated by the zone melting method [10-12], and Furuya et al. [5] and Hirano et al. [13] have reported the fabrication of silver added YBCO composites, but the distribution and behavior of Ag are not investigated in detail"

Jan 1, 2000

This paper describes techniques that have been used at RixÆs Creek Colliery to control blast vibration from throwblasts that face a residential area 4 km in front of the face. The paper describes blast design, face control including laser profiling, selective loading of blastholes after borehole camera surveys, and techniques used to assess the effect of burden variation, the cumulative effect of drilling and delay sequence, and the effects of meteorology.

Jan 1, 2001

By W. C. Hellyer

In an autogenous grinding circuit in which feed at approximately nine inches top size is reduced to a size suitable for subsequent processing, the build- up of a "critical size" fraction in the media causes problems. A "critical size" fraction has been defined as, "media too small to effect reduction by impact grinding of ore coarser than a quarter of an inch and too large to be broken by the largest size of media in the charge. 9, (1) The buildup of a "critical size" fraction reduces the capacity of the mill, increases the grinding power requirements per ton of finished product, and generally produces a finer grind than is desired. It is general practice to overcome this problem by the addition of large diameter steel balls to the grinding charge. This has certain disadvantages, such as; (i) an increase in mill liner wear; (ii) wear on the steel balls, and; (iii) some loss in flexibility in grinding circuit operations resulting from difficulties in removing the steel balls by means other than by grinding out.

Jan 1, 1970

By John M. Hird

Texas Gulf Sulphur Company's Lee Creek Mine has opened a major phosphate mining district in the Central Coastal Plains of North Carolina (Fig. 1). The ore deposit as it is now known was roughly outlined in 1961 by a Texas Gulf geologist using wire line exploration methods. Slightly uraniferous phosphate materials were detected by a slim-hole gamma ray probe run in numerous farmers' water wells penetrating the formations. A follow-up-core drilling pro- gram determined the economic ore limits to lie in the south central section of Beaufort County beneath 70 feet to 120 feet of unconsolidated sediments. The 50,000 acre deposit is known to contain over two billion tons of phosphate ore amenable to strip mining methods. A part of the deposit underlies several thousand acres of the Pamlico River estuary. The 90 million dollar capital investment plant built by Texas Gulf during 1965-66 included a strip mining operation using a 72-yard walking dragline, a three million product ton per year flotation concentrator, four fluid bed calciners, a sulphuric acid plant (acid for captive use), a phosphoric acid plant, and three solid fertilizer material plants. Shipment to domestic markets is by rail and truck and to over- seas markets by barge to a transshipment terminal at Morehead City, North Carolina. Early mining investigations were conclusive first that the phosphate ore could economically be recovered only by dry strip mining methods, and second that artesian ground waters in the formation (Castle Hayne limestone) underlying the ore would have to be controlled. This report will relate the application of ground water hydrology in depressurizing the Castle Hayne aquifer to facilitate dry strip mining at depths 130 feet below sea level at the Lee Creek Mine.

Jan 1, 1970

By André Pomerleau, Michel Grégoire, René del Villar

"The operation of industrial flotation columns requires the control of at least two variables, the interface position and the bias rate, by manipulation of some appropriate operating variables. Problems arise due to the reliability of existing methods of measuring the bias (i.e bias = tailings water - feed water), a situation which has often forced the industry to disregard this control loop. Moreover, when using such a measuring approach, the identification of the process dynamics is impossible. A second problem arises from the possible interaction between both control loops that might call for the use of a more complex multivariable control strategy.Recent work done at Lava1 University has demonstrated the feasibility of an independent sensor for bias, which models the relation between the conductivity profile across the interface and the bias value using a neural network algorithm. A 250 cm height, 5.25 cm diameter Plexiglas laboratory column was equipped with a series of conductivity electrodes in its uppermost part (across the interface) to measure both interface position and bias rate. Using such equipment, the flotation column dynamics were identified. The results thus obtained permitted the design and implementation of a distributed PI control strategy, where bias was associated to wash water rate and froth depth to tails rate. Both PI controllers were tuned using a frequency-response tuning method. Results of both identification and process control are presented and discussed.INTRODUCTIONFlotation columns are used for the separation of valuable minerals from a carrier gangue. Typically, this device is a tall (9 to 14 m height) cylinder (1 to 3 m in diameter) although other cross sectional shapes are also used. Finely ground ore is fed as a pulp at about 2 m from the top of the column, and pressurized air is introduced through a sparger at the bottom. If the pulp has been properly conditioned with adequate chemical reagents (collectors and modifiers), the valuable mineral particles falling by gravity will attach themselves to the rising air bubbles, and the air-particle aggregates will rise to the top of the column where they overflow as a stream called the concentrate. The gangue particles,, that do not attach to the air bubbles, fall down the column being withdrawn at its bottom in a stream called the tails.A particular characteristic of flotation columns is the addition of a fine spray of water at the top. As the water flows down through the froth zone, it washes out the entrained gangue particles from the mineralized bubbles, thus improving the quality of the concentrate recovered at the top. As a result of its cleaning action, this water stream is called the wash water and the upper zone, the cleaning zone. In order to ensure a downward flow of wash water, a proper water balance must be kept in the froth zone, otherwise the water added at the top might shortcircuit to the concentrate without performing any cleaning action. This net downward flow of water inside the froth zone is called the bias and represents an important operating variable of a flotation column."

Jan 1, 1999

By Hector O. Romero, Paulo C. Fernández A, Christian Rees Prado, Claudio C. Gajardo

In open-pit mining, estimating post blasting displacement and spillage accurately is essential to guarantee operational efficiency, ensure alignment with production plans and their associated key performance indicators. The absence of predictive modeling tools on blasting operations results in several critical challenges, including operational reworks due to deviations in material displacement, significant discrepancies between mine and plant (ore grade dilution included), misalignment with the reported production plan, and increased operational costs due to inefficient use of resources. This study, conducted at Los Bronces Mine operated by Angloamerican, Chile, addresses the application of a three-dimensional simulation tool that, through numerical modeling, is capable of predicting post blast rock displacement. The implementation was carried out in a pit phase characterized by blasts near the pit boundaries, with a high risk of material spillage and potential blockage of the only access ramp to the extraction levels. By the integration of key design parameters, such as blast pattern geometry, detonating time, explosive charge distribution and pre and post blast survey, an optimal calibration was achieved and validated in seven blasting events to date, reaching an accuracy greater than 80% in estimating post-blast rock displacement and spillage volumes. Furthermore, this study allowed the evaluation of different pattern alternatives with and without spillage mitigation measures (use of air decks near the free face), obtaining a high correlation and accuracy exceeding 95% in predicting the selected design outcome, supporting optimal design selections. The result highlights the usefulness of the model as a decision-support tool for blasting engineers and short-term planning, by reducing the need for unnecessary operational reworks, improving geological and operational reconciliation, and ensuring the alignment of the extracting plan with production targets. The current average deviation is 15%, with higher deviations observed in blasts with smaller volumes of spill or where the simulated sequence was changed before blasting. The use of this type of three-dimensional numerical modeling represents a significant advancement for blast engineering and the optimization of key performance indicators in open-pit mining operations.

Jan 26, 2026

By J. P. McDonnell, L. A. Beckett, K. Y. Hammy

Dangerously high stress areas can be controlled by proper mine planning and/or destressing. This paper reviews practical methods to detect and destress high-stress zones along coal faces. The US Bureau of Mines investigated stress-related burst problems and destressing efforts at a cooperating mine. Laboratory tests of the drilling yield method for high stress detection were conducted to determine the correlation between the volume of cuttings obtained and the magnitude of the applied stress. A three- dimemiom1 computer modeling program was used to evaluate the effectiveness of stress relief methods.

Jan 1, 1987

By Raja V. Ramani

Worldwide, promulgation and enforcement of health and safety laws and regulations have been the primary means of ensuring minimum and uniform standards of health and safety in the mining industry. In U.S. coal mines, a new era was ushered-in in 1969 for the control of health hazards from respirable coal mine dust. Since then significant progress has been made on all aspects of the respirable dust problem-its definition, monitoring, reduction, and control. In the intervening years, our ability to monitor, analyze, and characterize the mine atmospheric environment and the health of miners has increased many fold. Also, advancements in production technology have far outdistanced enhancements in environmental control technology. Therefore, questions are continuing to be raised on the adequacy of the characterization and control measures with regard to both the airborne respirable dust in mines and the health effects of respirable dust. Late in 1995, the Secretary of Labor appointed an Advisory Committee on the Elimination of Pneumoconiosis Amona Coal " Mine Workers (Dust Advisory Committee) to review the progress towards elimination of coal worker's pneumoconiosis (CWP) and silicosis, and in the program to control respirable coal mine dust in underground and surface mines, and make recommendations including improved standards and other appropriate measures for the control of exposure to airborne coal mine dust. The Committee's report was released in October, 1996. In this paper, a summary of the recommendations of the Committee is presented. A brief discussion of the background, and the issues and findings leading to the recommendations is also presented. The Committee concluded that the progress made towards making mines safer from the health hazards of respirable coal mine dust is substantial but that it is not sufficient to achieve the intent of the 1969 Coal Act. The Committee's recommendations encompass a wide range of issues addressing permissible exposure limits (PELS), sampling, dust control plans, hazard and medical surveillances, role of miners, training, and research and development.

Jan 1, 1997

By Jon C. Yingling

A control system for reducing peak loads on mine conveyor networks is proposed. The system involves continuous monitoring of flows into the conveyor network and section feeders with variable discharge capability. The control strategy uses differences in material transit times from various production units to the transfer points in the network to forecast load levels that will be intersected by the discharge of the controlled feeders over future time intervals. Feeder setpoint adjustments are made to prevent excessive peaks in the combined flows at the transfer points, while maintaining adequate feeder throughflow to avoid production bottlenecks.

Jan 1, 1992

By C. J. Brown

Controlling the level of impurities in copper refinery electrolytes is essential to achieving acceptable cathode purity. Purge of electrolyte is not an entirely satisfactory solution since the cost of neutralization, waste disposal, and replacement acid can be appreciable. The APU® process utilizes ion exchange resin to sorb sulphuric acid while rejecting metal salt impurities. Extensively employed for recovery of waste pickling and anodizing acids since 1977, the system is now being used at several refineries for removal of contaminants such as antimony, bismuth, iron, and nickel. The purified acid, which is recovered from the resin by water elution, is recycled back to the refinery tank-house, while the metals are typically recovered from the de-acidified by-product solution by precipitation.

Jan 1, 2005

By C. L. McKenzie

American Girl Mine is located in the Cargo Muchacho Mountains in the southeastern Imperial Valley of Southern California. Production from the current open pit mine and heap leach recovery system began in early 1989. Previous mining and gold recovery took place commencing in 1987 at the Padre Madre site, situated adjacent to the American Girl site to the southwest. In mid-1990, a 790-tonne-per-day underground gold mine and mill went into production. Approximately 6,500 troy ounces of gold per month are recovered from the combined open pit underground mine operation. Copper in the form of Azurite [Cu3(CO3)2(OH)2] and Malachite [Cu2CO3(OH)2] are abundant in the mined ores (Henshaw, 1942). The high solubility of these minerals in caustic cyanide solutions has a negative impact on carbon adsorption and electrowin processes. This paper presents the results of monitoring programs, process chemistry, and control changes introduced at American Girl Mine to abate production complications in the refinery and measures taken to minimize solution gold losses in the adsorption circuit(s).

Jan 1, 1993