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By Wendell H. Nielson

Flotation processes contain disturbances which make material balance closures difficult to achieve. Lack of closure also arises from instrument errors. A portion of these problems can be overcome by proper equipment selection; the primary measurement installation and methods of initial data filtering are discussed below. The problem of data adjustment has been considered before (2). The technique described here is essentially that of Ripps (2). The technique was expanded to include linearization of non-linear material balance equations. An additional large error detection portion was also added to Ripp's formulation. Ripp's technique is based on a Lagrange-Multiplier optimization method. The Lagrange-Multiplier technique is generally applied when there are equality constraints on the variables. Steady-state material balance equations fit in this category. The basic Lagrange-Multiplier method is described. It is followed by a description of the modified material balance data adjustment technique. An example is presented to illustrate the use of this method.

Jan 1, 1970

By J. W. Carson

Introduction Many bulk solids such as coal, limestone, and fine moist ores often flow unpredictably out of bins, hoppers, and boreholes. Vast amounts of time and money are spent-with or without success-on flow promoting devices. In addition, many solids segregate in storage, feed erratically, flood, arch, rathole, and stick to bin walls reducing the live capacity. This article discusses bulk solids flow properties and provides guidelines for designing storage bins, hoppers, and feeders to provide reliable flow. Bulk Solids A bulk solid is a granular material consisting of discrete solid particles-submicron to several inches in size-that is handled in bulk form (for example, in a bin or silo). The gas filling the voids is generally insufficient to fluidize the material and the liquid (usually water) content is assumed to be less than saturation. Types of Flow Problems To design an efficient storage system, an engineer must be aware of problems that can arise during storage and flow of bulk solids: • No flow. A stable arch or pipe (rathole) develops within the solid, stopping flow. • Erratic flow. Momentary arches form within the solid, (ratholes), partly or completely empty out, and then collapse. • Flushing. Powders become fluidized, aerate, and flush uncontrollably through the bin outlet. • Lack of design capacity. A large part of the stored material remains stable around a rathole. Manual prodding, severe vibration, and even explosives may be used to restore flow. • Segregation. Smaller particles tend to sift through the voids between larger particles causing accumulations of fines and coarse in various areas of the bin. • Product degradation. Some materials spoil, cake, or oxidize if they remain in a bin too long. This is usually caused by a first-in-last-out flow sequence. • Level control. Measuring the volume of material left in a bin is difficult if a rathole develops. In one portion of the bin the level control device may indicate the bin is full; in another portion it may indicate it is empty. Eliminating Flow Problems All flow problems can be minimized or prevented by suitable design of the bin/feeder unit. This involves knowing the flow properties of the solid, then choosing the appropriate type of bin and feeder to establish the desired flow pattern. There are three types of flow patterns that may occur in a bin: funnel flow, mass flow, and expanded flow. Funnel flow occurs when some of the material in the bin is stationary while the rest is in motion. Funnel flow bins, shown in Fig. 1, are characterized by: • Low head room. A flat bottom or shallow hopper bin has large storage capacity with minimum height. Unfortunately, all this storage capacity may not be usable ("live"). • First-in-last-out flow sequence. The first material put into a funnel flow bin is the last material withdrawn because the flowing material is concentrated in the region directly above the outlet. • Ratholes. Because of the flow channel that forms, a stable rathole develops if the material has sufficient cohesive strength. • Erratic flow. Once a rathole becomes partially or completely empty, it may collapse creating a stable arch and erratic flow. • Flushing. Collapsing ratholes cause flushing and flooding of fine material. • Segregation. If a bulk solid has a tendency to segregate, this tendency will be accentuated as the material is discharged from a funnel flow bin. Funnel flow bins are suitable for coarse, free flowing, nondegrading solids, when segregation is not important. Mass flow occurs when all the material in a bin is in motion whenever any is withdrawn. Char-

Jan 3, 1983

By Charles Rubin

Mining is a capital- and labor-intensive business, and profitability often depends on the ability to squeeze maximum efficiency out of every piece of equipment to achieve safe production. This means keeping every mechanized drill, loader, truck and bulldozer operating at all times, and having a system to coordinate the movements of people and personnel. Mines often use wireless radios to connect equipment with management systems. But growth and changes in a mine?s profile over time can require upgrades to the wireless network. In its openpit gold mine near Carlin, NV, Newmont Mining Corp. has recently upgraded to microwave radio systems to increase bandwidth while maintaining round-the-clock uptime on its wireless network. For many of its operations around the world, Newmont uses Minestar, an operational control software system that allows administrators to dispatch equipment operators and use GPS to track the precise position of every piece of equipment in an operation. Each of the approximately 150 pieces of equipment at the mine has a radio on board. These radios connect to a network backbone that carries information between the equipment and the mine?s operations center. When traffic began to bog down on this network, Newmont upgraded to Exalt microwave backhaul systems to carry dispatch, inventory and control information throughout its operation.

Jan 4, 2010

By R. Q. Honaker

Recent studies conducted at Virginia Tech have shown that ultrafine coal particles can be selectively coagulated and separated from mineral matter without the use of traditional agglomerants or flocculating agents. This technique utilizes hydrophobic interaction forces to induce coagulation of coal particles, while particles of mineral matter are dispersed using pH control. After selective coagulation, the coal coagula can be recovered by a sedimentation technique. In the present work, factors such as pH, particle size, and solids concentration have been examined. A wide range of coal samples have been successfully upgraded using this technique.

Jan 1, 1991

By Joseph R. Wojcik

Introduction Placer deposits account for one-half to two-thirds of the total gold produced worldwide. As many as 311 t (10 million oz) have been produced from some major districts. Several others are credited with 155 t (5 million oz). All the major districts and many lesser ones have similar characteristics. Consideration of these characteristics offers insight into the origin of gold in the deposit. Knowing the gold deposit's geologic history leads to useful conclusions in exploring for placer deposits and for deposits in consolidated areas. Placer Deposit Characteristics Table 1 lists 17 placer gold districts around the world and their characteristics. These include type and age of, mineralized source rocks, associated intrusive rocks, and age of intermediate sedimentary cycles. Although quartzite or sandstone occurs in the bedrock sequence in four of the 17 districts, slates, phyllites, or schists are present in all of the districts. Additionally, in all but three, the slates are pre-Mesozoic. And, in six of the remaining 14, the slates are Precambrian. Rocks intrusive into the slates are all of intermediate to acidic composition and are emplaced as stocks, dikes, or sills, rather than being batholithic in proportions. Intermediate interceptors have not been recognized in only three of the 17 districts. Data from China and Mongolia are inconclusive as to this characteristic. Black Shale Gold Higher than average gold values are found in modern sedimentary rocks in coarse granulites, conglomerates, sandstones, and gray-wackes. Not so predictably, higher than average gold values also occur in black shales and carbonaceous argillities. Li and Shokena (1974) found that, in the Proterozoic sedimentary and equivalent metamorphic rocks of the Enisei Ridge, carbonaceous and graphitic phyllites and schists were particularly enriched in gold. Korotayeva and Polikarpochkin (1969) reported gold content in organic rocks to be enriched up to 15 times more than the organic free shales and siltstones of the Nerchinsk Zavod region of eastern Transbaikal. Black shales can be gold interceptors as are rocks of the granulite facies. Gold occurs in shales in particulate, free form, in pyrite, adsorbed on clays, and precipitated on carbon. In copper-bearing shales of Poland's Fore-Sudetic monocline, Kucha (1973) reported gold present in organic compounds as well as in silver bearing minerals. Anoshin (1969) found a strong correlation between gold and the pelitic fraction of sediments in certain rocks of the Atlantic Ocean basin. Heavy metal absorption on clays results in agglomeration to the extent that the particles settle with the heavy mineral fraction in enriched strata. Piper and Graef (1974) think that gold in sediments on the flank of the East Pacific rise is of lithogenic origin. Crockett (1973), however, proposed a volcanogenic exhalative origin. A strong correlation between gold and volcanic activity exists in rocks of the Canadian Shield where tuffaceous sediments and porphyries are more frequently enriched in gold than rocks with no volcanic components. Volcanic rocks of intermediate to acidic composition are considered here to be the primary source of gold in black shales. Gold is concentrated in shales as detrital free grains with diameters less than 50 µm (270 mesh), as precipitates, and in pyrite or other sulfide minerals. This is the first step in the history of gold placer deposits. Grain Size Modification Gold, as free grains with diameters less than 50 µm (270 mesh), is too light to be concentrated hydraulically into placer deposits. Some process has increased the average size of the gold grains. Mobilization during regional metamorphism converts most of the gold into particulate grains or entrains it in microfractures in the sulfide minerals. With moderate folding, small, white, vitreous quartz veins develop. As deformation continues, larger, more conspicuous quartz veins are formed. The larger veins are folded and faulted and contain native gold as minute specks and flakes not visi-

Jan 11, 1984

By G. A. Kosick, L. Kuehn

The design of an information management system (IMS) for a mineral processing plant requires prior consideration of many factors, which can be broadly categorized into two domains, process plant considerations and IMS considerations. The process plant considerations include: plant characteristics, management and personnel issues, existing organizational standards and policies, and the level of existing hardware and software systems. The IMS considerations include: system functionality, system sizing and desired performance, hardware components, software components, and system support issues. All of these aspects must be addressed in order to achieve a functionally successful and cost effective system. The purpose of this paper is to lay out these design issues and, in doing so, to provide process engineers with a guideline with which to tailor a system that is best suited to their specific application. The paper is completed by presenting an approach that has been used in two Canadian concentrators. Both of these plants have incorporated MillEX, a software system designed specifically as the central component of a mineral processing IMS.

Jan 1, 1993

By J. J. Kellar, W. M. Cross, J. D. Miller

Infrared spectroscopy has been one of the most useful experimental techniques for the analysis of surface reactions in flotation systems, including surface alteration and surfactant adsorption reactions. With the advent of Fourier transform infrared (FTIR) spectrometers, many low-energy throughput IR experimental techniques previously unused by flotation researchers have come into greater use. In particular, internal reflection spectroscopy (IRS) is the most often used technique for in-situ studies. To date, three IRS methods have been used for in-situ measurements. These techniques are evaluated for use in characterization of surface reactions in flotation systems. The method using mineral crystals as reactive internal reflection elements (IRE) is of particular interest because it allows surfactant adsorption densities to be calculated directly from in-situ spectral data in real time. Application of in-situ FTIR/IRS with reactive internal reflection elements will be demonstrated for collector adsorption reactions in each of the major flotation systems. The alumina (A1203)/sodium dodecylsulfate system is used as an example for insoluble oxide/silicate flotation, while the fluorite (CaF2)/oleate system serves as a paradigm for semisoluble salt flotation. For sulfide flotation, sphalerite (ZnS) is used as the reactive IRE with potassium amylxanthate and potassium ethylxanthate as collectors. In the case of soluble salt flotation, sylvite (KC1) is used as the IRE with n-octylamine as collector. Finally, the use of reactive IREs in the near-IR spectral region and in spectroelectrochemical research is discussed.

Jan 1, 1989

By R. J. Sterrett

To the average mine operator, the implementation of environmental regulations are viewed as a drain on the profitability of the mine. Since the birth of environmental awareness in the late 1960's, which led to the passage of the National Environmental Policy Act (NEPA) in 1969, and through the publicity brought about by the discovery of Love Canal in 1978, the public are clamoring for increased environmental protection. It should be emphasized that the concern regarding the issues of the handling and disposal of nuclear and toxic wastes is not limited to a few overzealous environmental advocates. Toxic waste issues have "grass roots" interest and support. A reflection of this support has been the passage of key pieces of federal legislation. . Of particular interest are the following acts: Clean Water, Toxic Substances Control, Surface Mine Land Reclamation, the Resource Conservation and Recovery Act (RCRA) and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). The last act is often referred to as "Superfund". Both RCRA and CERCLA have been re-authorized and amended, and in their re-authorization they have been substantially strengthened. Of the last two pieces of legislation, RCRA is the most powerful in that it governs the handling of hazardous wastes from "birth to grave". CERCLA was established to cleanup abandoned waste sites which are threatening human health or the environment. These cleanups can be undertaken by the government and then billed back to the previous owners or to the disposers at the sites.

Jan 1, 1988

By R. Candia

The use of industrial wastes, such as quarry fines of crushed stone, should represent a basic component of sustainable development indicators. Therefore, increasing investments should be foreseen in techniques of treatment and recycling of residues in mining, as well as by-product attainment that generate jobs and income. The standards of identification and discarding of industrial wastes vary significantly between countries. However, practically all nations have started becoming more restrictive regarding environmental legislation, especially concerning production, transport, treatment, recycling and final discarding of industrial wastes. Under an environmental point of view, solid wastes produced by a system (such as a quarry) can be handled in two ways: a) they can be discarded in piles or b) they can be internally or externally recycled and reused. This second practice is translated to an additional economic consequence such as an increase of income as well as a decreased environmental impact. This option is more advanced and should be included in company policy. This paper presents cases where this practice is used, i.e. diminishing the environmental liabilities through the use of the quarry fines in the manufacture of industrial devices, incorporating such wastes in the productive chain, instead of storing them in piles.

Jan 1, 2007

By L. Shwydiuk, A. Chrzanowski, W. Newcomen, G. Bastin, R. Wilkins

Automated monitoring of steep embankments allows the early detection of instability and can be used to avoid or mitigate possible slope failures. A system that uses multiple and different types of sensors has been created and successfully tested at the Highland Valley Copper mine in British Columbia. The system uses robotic total stations (RTSs) as the primary measurement sensor, with surveys repeated at predefined intervals selected to optimize operational efficiency. A methodology has been developed to improve the system’s accuracy and reliability by reducing the effects of systematic errors created by atmospheric refraction and unstable instrument and reference point positions. The inclusion of GPS sensors to monitor the RTS positions creates additional operational flexibility and maintains system integrity when insufficient reference stations are available.

Jan 1, 2003

By Donn A. Calder, Wayne C. Henderson

The Calmet Process for extraction and recovery of gold and silver from concentrates and high:grade ores has been a commercial reality for over two years. During that time period, almost seventy-five different concentrate (or ore) types have been processed in approximately 200 separate lots (a total of almost 2000 short tons). During commercial operation of the process at the plant in Fountain, Colorado, recovery of gold and silver into <lore' has averaged almost 93% for gold (range 81-98%) and over 90% for silver (range 76-97%) based on a fire assay target and calculated head values.

Jan 1, 1998

By J. A. Herbst, R. Zaragoza

Conventional control schemes in use today are not able to produce satisfactory control when high-frequency disturbances are present in the flotation feed. An advanced model-based control scheme is presented here as a promising solution to this control problem. The main feature of this control scheme is the real time identification of the unknown disturbances in the first few cells of the flotation circuit. This information is used to control the rest of the flotation plant in a feedforward fashion. This control scheme also provides flexibility to meet any metallurgical, economical, or management objective.

Jan 1, 1987

By S. Hicks

This technical note describes an alternative procedure that can be used in linear programming calculations where the compliance limit of lbs SO2/million Btu for the blending coal is subject to change. Dr. Mateer in his technical note titled "Coal blending for sulfur compliance" (ME, September 1994, p. 1103) defined an "excess sulfur" parameter that provides a valid constraint equation for a linear program optimization. The coals used by Dr. Mateer in his examples are shown in Table 1. To create the parameters for the constraint equations to blend to an SO2 content of 1.2 lbs SO2/million Btu, the excess sulfur for Coal A was defined as Sulfur excess% = 0.5 - 0.6*13,000/10,000 = -0.28 This equation was used to create the constraint equation -0.28A + 0.44B + 1.36C[<] 0.0 Another way to create the parameters for the constraint equation is given below. In these equations: •W is the total weight; •A, B and C are the fractional proportions of each potential blend stocks; •Sa, Sb and Sc represent the percent sulfur content of the blend stocks; •Ha, Hb and Hc represent the calorific content of the blend stocks in Btu/lb; and •H and S represent calorific and sulfur contents of the composite blend. The weight of blend to produce one million Btu is [ ]

Jan 1, 1998

By William R. Sharp

This paper describes a graphics station and graphics software designed specifically for use within the minerals industry. Through the graphics station, a user is able to recall maps for modification, display them on a color CRT, send the work to a plotter, and restore the work when finished. The engineer may use the system for the storing of data, per- forming engineering calculations, doing word processing, and performing general file maintenance. In addition, the system may be used to communicate with a mainframe computer for such purposes as: transmission of large data files, graphic 3-dimensional rotation of a mineral deposit or mine design, contouring of spacial data, and other data processing work.

Jan 1, 1982

By T. V. Vasudevan

Floc properties such as density, size, size distribution, porosity, and shear strength govern the effectiveness of flocculation as a process for solid-liquid separation. The floc characteristics desired for removal of suspended solids by sedimentation or filtration, for example, are known to he different. In this study, an attempt has been made to evaluate the effects of various physical and chemical factors on the density and shear strength of the flocs.

Jan 1, 1990

By Walter E. McCulloch

Installation of flash flotation in the copper concentrator of Freeport Indonesia in late 1986 and 1987 increased gold recovery by about 13%, while also increasing concentrator throughput. Copper recovery remained essentially the same. Flash flotation has since been included in a recently completed mill throughput expansion to 32,000 t/d (35,300 stpd) as well as in a current expansion to 52,000 t/d (57,300 stpd).

Jan 1, 1991

By D. W. Hill

By seeking to define the social and political parameters of both established and potential uses of the underground, this paper will attempt to formulate and state the problem posed in the realms of public choice for obtaining more rapid development and more beneficial use of the underground environments. Essentially, the paper will pursue the following outline: 1. Established policies and established uses of the underground 2. Potential uses of the underground for social benefit 3. Constraints on development and policy a. Psychological constraints b. R & D plus physical constraints c. Economic constraints d. Public choice and policy contraints (both governmental and non-governmental) e. Legal and other structural constraints 4. Defining the problem from the social standpoint 5. Suggestions for surmounting the constraints and meeting the problem: some hypotheses for the future.

Jan 1, 1974

By V. R. Degner

Given: the process tonnage, performance objectives, and plant floor area, the paper will outline the metallurgical and machine hydrodynamic scale-up procedures for translating the lab flotation test results to the design of a full size flotation machine installation, including the machine number, size, and arrangement. Machine selection considerations for rougher, scavenger and cleaner duty, and special considerations relative to specific applications, will be summarized where appropriate. The value of kinetic modeling in quantitative metallurgical (lab to full size machine) scale-up will be reviewed considering a coal installation, and design information for additional applications such as copper, molybdenum, iron, phosphate, and potash will be discussed.

Jan 1, 1986

By R. L. Garrett

The quality of mineral additives used in a drilling fluid (mud) can dramatically affect the fluid&apos;s properties and the overall cost of drilling an oil or gas well. The principally wed minerals are bentonite, barite, barite/hematite blends, and hematite alone. The high specific gravity minerals, barite and hematite, are used to increase drilling fluid density. Bentonite clay is used to increase drilling fluid viscosity and gel strength and to provide a low permeability filter cake. A multimillion dollar investment in a well and the safety of the personnel on the drilling rig can depend on how effectively these mud additives perform with other constituents in the mud. This paper points out effects caused by small amounts of certain carbonate and sulfide mineral impurities in barite or hematite and how polymeric extender additives in bentonites contribute to unpredictable behavior of a mud. Effects like these are the reason oil companies using these materials sometimes set their own quality standards beyond those already specified in APZ Spec. 13A. Also discussed in this paper are the current standardization activities of API Committee 13 on these minerals.

Jan 1, 1988

By W. Z. “Ben” Wu

The investigation provides a method of efficiency evaluation among several kinds of tools employed to cut different types of rocks. A ballistic test stand incorporated with a modified Hopkinson bar was used to simulate a percussive drilling tool. An Apple IIe microcomputer was employed for high speed data acquisition and numerical analysis. A newly developed method for remote monitoring the rock-tool interaction, including contact force, bit penetration and energy transmission,is presented in the paper. Theoretical predictions and experimental results appear in faily good agreement

Jan 1, 1986