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By John H. Bassarear, A. A. Dor

INTRODUCTION Primary grinding mills as defined in this paper, are autogenous or semi-autogenous rotating, tumbling mills having a coarse feed with a top size usually varying from 150 to 300 mm (6 to 12 inches). Most frequently, the feed to these mills is the product of primary crushing plants but in some cases run of mine ore is used as feed such as at Benguet, McDermitt, L-Bar Sohio, Bear Creek and others. The size of the largest lumps in the mill feed is principally determined by limits set by the mill feed trunnion diameter and by the type and size of conveying equipment used for handling and of bins and stockpiles used for storage. The use of primary mills in mineral processing plants has expanded very significantly in the last twenty years, and they have been successfully applied to the treatment of a wide variety of ores in both wet and dry grinding applications. In the present state of technological development for primary grinding mills, there is a wide choice of acceptable options with respect to type and size, grinding flowsheet and grinding media. The choice of the optimum combination which would result in the most satisfactory condition of operation, from the standpoint of both metallurgical results and costs, depends on the nature of the ore, the required characteristics of the grinding products and on various geographic and economic circumstances. The effects of such factors and considerations on the choice and sizing of primary grinding mills and flowsheets are reviewed and discussed in the following pages. PRIMARY MILLS SELECTION Inherent Characteristics of Primary Grinding Primary grinding is complex because it involves several comminution mechanisms which occur simultaneously and to some degree interfere with one another. These mechanisms of impact, attrition and abrasion have been described earlier. The relative importance of these three main grinding actions and their mutual balance resulting in a continuous uniform operation of the mill depend to a very large extent on the nature of the ore and its physical properties. Homogenous, single mineral ores will behave quite differently from heterogenous ores consisting of different minerals bound together along defined

Jan 1, 1982

By Farrel W. Lytle

An X-ray emission spectrographic method of analysis is presented for determining rare-earth elements in fractions obtained from bastnaesite ore. The method includes determination of yttrium, thorium, lanthanum, and the rare-earth elements in various complex mixtures. The analysis technique is based upon comparing the samples with synthetic standards approximating the composition of the samples. Working curves are plotted on an absolute-intensity basis, with no correction for back-ground. Examples of working curves and the analyses of typical rare-earth concentrates are included. The selection of spectral lines for the various sample matrices is discussed. A special technique is used for samples in which rapid hydration and carbonation occurred. By analyzing synthetic samples of known composition, the accuracy of the method was determined. The average error of analysis was about 3 percent of the amount present in the range from 5 to 100 percent and about 7 percent in the 0.2-to 5-percent range. A maximum of about 40 samples per day may be analyzed for 7 elements each.

Jan 1, 1957

By Liow Jong-Leng

A survey of the interactions of large gas bubbles formed from top and bottom injection of gases into melts was carried out. Spherical cap bubbles were found not to produce much splash when they break through the bath free surface except for that formed by plunging of the-spout at its edges. In contrast, the bursting of balloons produces cavities which give rise to liquid jets being ejected from the bath free surface. The position of the balloons relative to the bath free surface is an important parameter in the formation of the liquid jet. It is found that the interactions of multiple bubbles close to the free surface is important in determining the splash behaviour of gas injected systems.

Jan 1, 1996

By Truman P. Stauffer

Secondary use of mined-out space in underground limestone quarries is emerging in the Kansas City area where abandoned quarry sites are being renovated into warehouses, factories, and offices. Mining techniques, ceiling heights, and pillar distribution are being altered as planning for the secondary use of mined-out space is combined with the quarrying process. Even the historic urban- quarry land use conflict invites a reappraisal in that this development provides a potential resolution of the problem. Mutual subsidization by dual rock and space interest is changing the economics of rock production. A city is much more than a surficial adjunct superimposed upon the topography of an area. Its development and growth are deeply rooted in the resources, benefits and problems of its underlying geology. The environmental geologist must address himself to more than the quality of a particular resource. He must comprehensively relate resource extraction and processing with the urban emphasis of optimal use which favors long term usage of land over one time economic ventures. Limestone quarrying, closely allied with the growth of many cities, has commonly left a series of scarred landscapes in the path of the burgeoning metropolis. These abandoned quarry sites are barriers to orderly city growth and fail to serve the people as useful and taxable land. Where quarries are functional, supplying the city with needed growth minerals, problems of blasting damage, noise, and dust exist. Technology faces the challenge of making mineral production and processing good neighbors to the urban market they serve. Continued growth of cities may require more efficient use of space below as well as above the surface optimizing land usage so that long term economic benefits may be reflected in improved mining methods.

Jan 1, 1973

By R. P. King

"A model of the flotation process can be used effectively for design and control. For design purposes it can be used to predict the performance of a large plant from laboratory and pilot plant data. It can be used for control purposes to assess the utility of any proposed operating modification to an existing plant, and it can also be used to determine optimal control settings for best operating performance.A model has been developed that will allow for variations in feed properties and for variations in fineness of grind. The model can be used to assess the effects of reagent addition rate, aeration rate and pulp level on plant performance and these are the control variables that are used individually or together in all operating flotation plants. The model provides for a distribution in the values for flotation rate constants, particle size and mineral fraction, and, because of its complexity, requires a large computer when it is to be applied to a typical plant configuration. The computational method that is used to apply this model to such configurations is described in this paper, and particular attention is paid to the problem of allowing for feedback of tailings from cleaners and recleaners."

Jan 1, 2014

By Hong Zhong, Shuai Wang, Zhanfang Cao, Ting Dai

"Manganese is widely used in industries such as the steel industry and is now an essential element in modern industry. Technologies for the efficient and clean utilization of manganese resources must be developed and employed to ensure the sustainable growth of the manganese industry. Our research focuses on the use of beneficiation technologies to improve the grade of ores or the replacement of low-grade manganese carbonate ores with high-grade manganese oxide ores, and thus, to reduce reagent and energy consumption and the yield of electrolytic manganese residues from metallurgical processes; the study of leachate purification technologies; the study of electrochemical behaviors during electrolysis and energy-saving electrolysis methods; the development of chromium-free passivators as alternatives to the highly toxic potassium dichromate passivator; the non-hazardous treatment and resource utilization of electrolytic manganese residues and other manganese by-products; and the development of new manganese products. INTRODUCTION Manganese is widely used in the steel industry, nonferrous metallurgy, the chemical industry, electronics, batteries, agriculture, etc. Globally, more than 90% of manganese is consumed by the steel industry, and thus, it is said that ""No steel industry without manganese""(Banerjee et al. 2017, Zhang et al. 2017). Current manganese resources mainly include manganese ores, marine manganese nodules and waste catalysts. The total global output of manganese ore from land deposits is 18 million tons (metal volume), and the reserves, most of which is in the form of manganese oxide ores, are estimated to be 620 million tons (metal volume). More than 400 manganese ore deposits with a total reserve of 1.22 billion tons have been discovered in China. These deposits are predominantly manganese carbonate ores. Marine manganese nodules exist on the surface of the deep seabed at depths of 2000-6000 m. These nodules, which are also called polymetallic nodules, manganese balls, manganese aggregates and manganese tumors, are mainly composed of iron and manganese oxides. The total reserves of these resources add up to more than 3 trillion tons. Furthermore, the manganese in manganese-containing catalysts can be recycled after they become inactive."

Jan 1, 2018

By A. L. Mular

A great deal of effort is being expended by mineral processing engineers to acquire a basic knowledge of modelling and optimization techniques. Stimuli such as immediate process improvement, expanded process understanding, optimal flowsheet design and re-design, and the development of new and better control systems are goals which excite the imagination in terms of increased profits. To reach these goals, process models and efficient optimization strategies, regardless of their purpose, assume an important role. Consequently, few of us can argue that such efforts are of no value. The purpose of this paper is to review empirical modelling methods and optimization strategies which appear to be of value to mineral engineers.

Jan 1, 1972

By J. O. Marsden

This paper presents an overview of the innovative methods for gold and silver extraction that have been put into actual practice in North America since 1987. It is an update of a paper of the same title which was presented by Sass and Mansanti at the AMC conference in San Francisco in 1987. New practices, new equipment and variations of older practices that have been introduced in the last five years are discussed in each of the following categories: process selection trends, comminution, gravity concentration, flotation, oxidation, agitated and vat leaching, heap leaching, solution concentration and purification, zinc precipitation, electrowinning, tailings disposal detoxification, and reclamation.

Jan 1, 1993

By Kenneth K. Humphreys

INTRODUCTION What is automation? Why automate? Webster's New Collegiate Dictionary defines automation as "the automatically controlled operation of an apparatus, process, or system by mechanical or electronic devices that take the place of human organs of observation, effort, and decision." This definition gives an implied answer to the second question, "Why automate?" Automation, automatic control devices, and process control equipment receive their justification in supplementing or replacing manpower, which results in decreased operating costs. In the past, processes were operated with the minimum amount of instruments needed merely to guide operators. Processes were manually con- trolled by the operator on the basis of simple temperature, pressure, flow, and level indications on a panel. Today the tendency is to design a new plant to operate in a fully automatic manner according to a preset pro- gram utilizing a minimum of manpower. In addition to this direct cost reduction in manual labor, increased equipment capacity results from uniformity of flow and uniform control of process variables. This control eliminates or minimizes surges and permits equipment to be operated at or near its ultimate capacity and, for a given material throughput, permits the use of smaller process equipment. Automatic control, therefore, be it in the field of coal processing or in any industrial field, is simply a problem of economics. Control equipment is justified in terms of its contribution toward increasing productivity, increasing profit margins, or producing a new and salable product at a profit. Instruments and control devices can be divided into two general groups: (1) units which measure and (2) units which both measure and control a process variable.

Jan 1, 1979

By R. Ehrlich, F. E. Crane

A consolidated porous medium is mathematically modeled by networks of irregularly shaped, interconnected pore channels. Mechanisms are described that form residual saturations during immiscible displacement both by entire pore channels being bypassed and by fluids being isolated by the movement of an interface within individual pore channels. This latter mechanism is shown to depend strongly on pore channel irregularity. Together, these mechanisms provide an explanation for the drainage-imbibition-hysteresis effect. The calculation of steady-state relative permeabilities, based on a pore-size distribution obtained from a Berea sandstone, is described. These relative permeability curves agree qualitatively with curves that are generally accepted to be typical for highly consolidated materials. In situations where interfacial effects predominate over viscous and gravitational effects, the following conclusions are reached. 1. Relative permeability at a given saturation is everywhere independent of flow rate. 2. Relative permeability is independent of viscosity ratio everywhere except at very low values of wetting-phase relative permeability. 3. Irreducible wetting-phase saturation following steady-state drainage decreases with increasing ratio of nonwetting- to wetting-phase viscosity. 4. lrreducible wetting-phase saturation following unsteady-state drainage is lower than fir steady-state drainage. 5. Irreducible nonwetting-phase saturation 101lowing imbibition is independent of viscosity ratio, whether or not the imbibition is carried out under steady- or unsteady-state conditions. Experiments qualithtiveIy verify the conclusions regarding unsteady-state residual wetting-phase saturation. Implications of these conclusions are discussed. INTRODUCTION Natural and artificial porous materials are generally composed of matrix substance brought together in a more or less random manner. This leads to the creation of a network of interconnected pore spaces of highly irregular shape. Since the geometry of such a network is impossible to describe, we can never obtain a complete description of its flow behavior. We can, however, abstract those properties of the porous medium pertinent to the type of flow under consideration, and thus obtain an adequate description of that flow. Thus, the Kozeny-Carmen equation, by considering a porous medium as a bundle of noninterconnecting capillary tubes, provides an adequate description of single-phase flow. With the addition of a saturation-dependent tortuosity parameter in two-phase flow to account for flow path elongation, the Kozeny-Carmen equation has been used to predict relative permeabilities for the displacement of a wetting liquid by a gas. 1-5 It has long been recognized that relative permeability depends not only on saturation but also on saturation history as we11.6,7 Naar and Henderson8 described a mathematical model in which differences between drainage and imbibition behavior are explained in terms of a bypassing mechanism by which oil is trapped during imbibition. Fatt9 proposed a model for a porous medium that consisted of regular networks of cylindrical tubes of randomly distributed radii. From this he calculated the drainage relative permeability curves. Moore and slobod,10 Rose and Witherspoon,11 and Rose and Cleary12 each considered flow in a pore doublet (a parallel arrangement of a small and large diameter cylindrical capillary tube). They concluded that, because of the different rates of flow in each tube, trapping would occur in one of the tubes; the extent of which would depend upon viscosity ratio and capillary pressure. They limited

Jan 1, 1970

By Gerhard Braüner

The present knowledge on ground movements and mining damage is mainly based on observations made when mining seamlike deposits. The studies, rules, and regulations in different countries agree in that the differential ground movements, especially the strain, account for the damage to structures. Accordingly, large buildings are particularly susceptible. The opinions on what amount of ground deformation induces what degree of structural damage are not quite uniform. Mining damage can be reduced or prevented by structural and/or underground precautions. The latter comprise measures for generally reducing the ground movements (leaving pillars, filling, partial extraction) and for reducing temporary movements (rapid extraction, specially arranged workings). Because the differential movements decrease with increasing depth of mining, safety pillars are largely dispensable at greater depths. Shafts are mainly affected by the vertical derivatives of rock displacements, but extraction in the vicinity of shafts is feasible even under difficult conditions. The theoretical concept of the ground movement process established in part 1 of this work is in qualitative agreement with the facts herein observed. As a quantitative approach, it should be applied to calculating ground surface movements rather than rock movements about underground openings. It can be extended by introducing more detailed strata characteristics.

Jan 1, 1973

By Robert M. Grogan

Fluorspar is the commercial name for fluorite, which is the mineral having the composition CaF2, calcium fluoride. Its valuable properties are due to its content of fluorine, and it is the only important commercial source of that element. The name is derived from the Latin fluere, to flow, because the mineral melts easily and is a good flux. History The mineral has been known since Greek and Roman times, when it was used for drinking cups and ornamental slabs. Various peoples including the Chinese and the American Indians have carved ornaments from large crystals. Its usefulness as a flux was known to Agricola, who wrote about it in 1546.1 Mining began in England about 1775 15 and at various places in the United States during the period 1820 to 1840.28 Substantial production was achieved first in the period 1888 to 1900 in consequence of the development and widespread adoption of the basic open hearth method of making steel, in which fluorspar is used as a flux. After that, production and usage was stimulated by growth in the steel, aluminum, chemical, and ceramic industries and accelerated by World Wars I and II. The organic fluorides called "Freons" entered the picture in 1931, and the use of anhydrous HF as a catalyst in the manufacture of alkylate for high octane fuel blends began in 1942. The development of the froth flotation process in the late 1920's, a differential flotation scheme for separating fluorspar from galena, sphalerite, and other minerals in the 1930's, and the application of heavy-media concentrating methods to the treatment of low-grade ores in the 1940's were outstanding technological contributions that enabled increased production of fluorspar concentrates. Composition and Properties Fluorite in its purest form contains 51.1 pct calcium and 48.9 pct fluorine. Substitution of small percentages of cerium and yttrium for calcium have been noted.4 Mechanical inclusions of gases and fluids such as petroleum and water, and of other solid minerals such as pyrite, marcasite, and chalcopyrite are common. The fluorspar of commerce contains attached and admixed mineral impurities, chiefly calcite, quartz, barite, celestite, and various sulfides. It is interesting that the purest commercial form in which the mineral is sold, acid grade concentrate, contains a minimum of 97 pct CaF2, and as such is of comparable purity to many reagents used in chemical laboratories. Fluorite has a marked tendency to occur in large, well-formed crystals sometimes six to ten inches on a side. It crystallizes in the isometric system, frequently forming cubic and octahedral crystals or combinations thereof. The mineral also occurs in massive and in earthy forms, and in crusts or globular aggregates with radial fibrous texture. Crystalline fluorspar exhibits a great array of colors, from colorless and water clear to yellow, blue, purple, green, rose, red, bluish and purplish black, and brown. The colors are often arranged in alternating bands parallel to cube faces. They may be altered by exposure to X-rays, heat, ultraviolet light, and pressure, and are caused by a variety of factors including the presence of trace impurities and displaced ions in the lattice. Sometimes the changes induced by X-rays can be reversed by ultraviolet radiation. The mineral has a hardness of 4, and is the model of that hardness on the Mobs scale.

Jan 1, 1960

By Paul Hughes

Purpose of Research ? What are the loading mechanics of paste against barricades? ? What is the capacity of the composite paste fill fences? ? Based on the loading mechanics of the paste, do the fill fences pose a risk of failure? Outline ? Glossary of Terms ? General Introduction ? Research Methodology ? Site Description ? Instrumentation Program ? Results ? Analysis ? Conclusions ? Recommendation for Future Work

May 1, 2008

By P. E. King

The U.S. Bureau of Mines is conducting an ongoing research project to better understand the phenomena involved within electric arcs utilized in electric furnace steelmaking. With a better understanding of the physical and electrical characteristics involved, dynamic or predictive control of electric arc furnaces may be possible. A mathematical model is presented, but not solved, and the system of coupled equations is analyzed. Characteristic parameters are used to determine relative importance. In this manner, significant quantities are dermed. The parameters found to contribute little to the system of equations of motion are ignored. A resultant simplified system is identified, and directions for further study are indicated toward control of electric arc furnaces.

Jan 1, 1990

By Weijia Guo

With the exploitation of coal resources, a large area of land had been affected by surface subsidence, causing conflicts between man and land to become more conspicuous by the day, affecting the life of general public, and constraining further development of the land. This paper predicts the subsidence areas according to the 10-year mining plan of the Jibei mining district as an example. A plan of environmental management was developed based on sciences and practical economics.

Jan 1, 2006

By Dods G. H, Hewitt W. V

Ashton Mining Limited is currently one of the active companies undertaking gold exploration in Indonesia. Presently 7 Contract of Work areas are being explored for hard rock and alluvial gold. Hard rock exploration is focussed on the Tertiary volcanic arc terrains in which a variety of epithermal mineralisation styles have been identified. At the regional stage remote sensing techniques using Landsat, Spot and SLAR imagery where available, and photogeological studies are carried out in parallel with regional reconnaissance fieldwork programmes. These involve geological mapping and geochemical drainage sampling. Remote sensing techniques have proven useful in both the extrapolation of known geology and the identification of tectonically favourable settings as controls to mineralisation and volcanicity. The variety of mineralisation styles and settings is reflected in the highly variable geochemical signatures encountered. This has necessitated the refinement of sampling methods and sample preparation techniques for pan concentrate, stream sediment and soil samples in specific project areas. At the detailed prospect stage, mapping with particular attention to structural controls, wallrock alteration assemblages identified by petrog- raphy and XRD clay mineralogy, have proved useful in focussing drill targets. Drilling to date has utilised conventional diamond core drilling methods, the use of lightweight, man-portable "Winkie"-type rigs and hammer auger bedrock sampling systems. Geophysics methods successfully employed on various projects have included airborne magnetics and radiometrics, detailed ground magnetic surveys, VLF-EM and SIROTEM.

Jan 1, 1991

By H. Kellerwessel

This paper refers to the new crushing and grinding process, which was invented by Professor Schönert (Ref.1), Clausthal, Germy (author of one of the papers presented at this meeting). The process is known as high pressure particle bed comminution or interparticle crushing. Several papers by Professor Schonert and his coworkers and by specialists of the companies producing the necessary equipment under license agreements already described fundamentals of the process, the equipment used, results of lab size and large scale tests and finally the first results of truly commercial operations (Ref .2 to 11). Therefore it should be sufficient to summarize the main facts here: - To a bed of bulk material a pressure of more than 50 MPa is applied. Comminution is achieved mainly by the pressure which one particle transfers to the other and not by squeezing single particles between the working surfaces of some crusher or grinding media.

Jan 1, 1987

By M. Vallée

Several reviews of mineral project performance in the past 35 years indicate a pattern of occasional, but recurrent, mining project failures due to shortcomings in geological information and estimation, mineral processing and metallurgical testing, feasibility study objectives and requirements, and project start-up methods. A commitment to quality assurance and continuous improvement methods and to obtaining “ENOUGH DATA, OF APPROPRIATE QUALITY” is essential. Recent international and Canadian proposals for mineral resource and ore reserve definitions have taken a nonprescriptive stance that will undermine the formulation of requirements, guidelines and industry standards for efficient deposit delineation and estimation, and for the determination of project feasibility. To help reduce problems, every feasibility study supporting a mine development and production decision should be based on objectives and methods adequate to reach completion targets similar to the bankers’, as a good business target for a profitable project. In a resource/reserve system, the use of reserve should be restricted to a project that meets required technical, economic and legal feasibility requirements for successful project implementation, and the definitions of these categories should provide explicit limits. Current shortcomings will limit the ability of the Qualified Person to provide “adequate professional practice,” fulfill his/her professional responsibilities to his employer or client and provide adequate information to the investing public. We must take advantage of present opportunities for Setting New Standards for the new Millennium.

Jan 1, 2000

By I. S. Blair

The introduction of the 36 MVA smelting furnace at Mufulira, and the experience gained during the first five years of operation have been described previously (6). Based on this experience the furnace was rebuilt in 1977., Details of the modifications made during this rebuild are described. Subsequent to the rebuild, refractory failures, particularly in the electrode ring bricks of the sprung arch roof, continued to cause concern, and repair and improved roof control methods are described. Electrode breakages continued, but developments in casing design and electrode preparation have resulted in significant improvements. Modifications in the electric furnace gas handling system are outlined, together with details of further changes to be implemented in the near future. The systems developed for metallurgical control of the furnace and the thermo-dynamics of the process are discussed. The electric furnace at Mufulira is now operating at above design production levels, and has decisively justified the choice of this technology in situations with inexpensive electric power. The potential for further increases in production capacity from the Mufulira unit, and improvements in design for new units are discussed.

Jan 1, 1983

By SANDVIK WHITE

The mining industry produces approximately 4-7% of global greenhouse gas (GHG) emissions. It is fundamental for mining operations to take immediate sustainable action to actively contribute to an emissions-free future for the next generations. The mining industry has traditionally relied heavily on diesel technology and transitioning to more sustainable solutions requires change management to drive cultural acceptance and new product development. Sandvik was interested to find out the lifetime emissions of a single drill rig and to compare similar application diesel and BEV drill rigs with same use profile to each other. That led the calculation and pondering towards comparing different countries and mine sites as well

Jan 1, 2023