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By D. D. Carda, S. Dunn, W. E. Dunn, T. Storbeck

Gold chlorination which will be presented in this paper is limited entirely to the use of gaseous chlorine in a fluidized bed reactor at elevated temperatures in the absence of aqueous water. The only water used in this process is that which is used in scrubbing the effluents. Low temperatures are defined as those below 500°C. All experimentation for this paper was carried out on a laboratory scale, with all calculations extrapolated frpm this. Some of the data is drawn from work with other projects which have been operated at pilot and larger scale.

Jan 1, 1998

By Bryan C. Smith, Duane R. Skidmore

Volumetric mass transfer coefficients and gas holdups were measured in a concentric tube airlift reactor designed for the microbial desulfurization of coal. The slurries were comprised of an acidified basal salts solution containing thirteen different weight percents of coal (74 µm Ohio #1) at three temperatures. An enhancement in the mass transfer coefficient, KLa, with respect to that measured in pure solution was found at weight percents of 5 (volume fraction solids, ES = 0.035) or less, the greatest enhancement being as great as 37% at approximately 2 weight percent (ES = J 0.014). At higher solids fractions, the mass transfer coefficient decreased with further solids additions, decreasing by as much as 91% at 40 weight percent coal (ES = 0.315). KLa increased with temperature at all solids concentrations, the greatest increase being 392% at 72°C vs that measured at 30°C. Gas holdup, EG decreased with all increases in solids loading by as much as 65% and increased by as much as 67% with temperature. KLa and EG were correlated with operating conditions separately, and the separate correlations combined to yield overall correlations for the mass transfer coefficient and for the gas holdup. The correlations are suitable for inclusion in system models devised earlier for microbial coal desulfurization processes, and may be used for design, operation and cost estimation for such systems.

Jan 1, 1989

By James L. Hendrix, R. Y. Wan, David W. Kappes, Jinrong Zhang, M. C. Fuerstenau, Terence E. Albert

A sulfidic flotation tailings ore, containing 1.14 gpt Au and 242.53 gpt Ag, was treated by low temperature chlorination roasting followed by cyanide or chloride leaching. Eighty per cent of Ag was recovered by cyanide leach when the ore was roasted at 350°C with 50 kg/ton calcium chloride. About seventy per cent of Au was made cyanide amenable by chlorination roasting at 400°C. A better Ag recovery, ninety per cent or over, was achieved by chloride (NaCl+HCl) leach. However, Au recovery was very poor by chloride leach. Ferric chloride, calcium chloride, and cupric chloride were compared as chlorinating agents for their effect on Au and Ag recovery. The study found that low temperature chlorination roasting is very effective for recovering Ag associated with stibnite and stannite. The best chlorinating agent for the test ore was found to be calcium chloride. Parallel roasting-leaching tests indicated that chlorination roasting was far superior over oxidation roasting for both gold and silver recovery.

Jan 1, 1993

By Peter Keppler, Stephen D. Bundy

"Due diligence" is a review or audit of a facility or business to assess and quantify risks and operating status before an acquisition. Due diligence findings can be used to negotiate the price, general terms, and indemnification provisions in the purchase and sales agreement. In addition to assessing out- standing liabilities, necessary capital improvements, and the adequacy of operating budgets, due diligence should include "nontechnical" considerations, such as local community acceptance and relations, and the effect on the company's public image and operations. This paper will discuss how these considerations can be addressed in the due diligence process and factored into the transaction. Also, innovative means for risk reduction and risk transfer, during and after the transaction, will be discussed.

Jan 1, 2001

By John Marshall

Silverton was the queen city of the western mining towns in the early 1900s. Located high in the San Juan Mountains, the town constantly grew and changed. Yet, it was subject to the vagaries and whims of economics, politics and disasters, natural or otherwise. Breweries, smelters and sawmills serviced Silverton's swelling mining population, which reached several thousand at its peak. Two trains a day ran from Durango to Silverton, in addition to trains running from Silverton over the top of Red Mountain on to Ironton. They ran up Cement Creek to the little town of Gladstone and up the Animas River Valley to Howardsville, Eureka and Animas Forks. During these prosperous times, construction flourished. There were plenty of wooden structures, and many of these stand today. The first brick buildings were built by bricklayer Patrick Stanley in 1877. It took quite a while for the first car to arrive. Almost 28 years passed from the coming of the first train to the arrival of the first car. It was brought over 3,840-m (12,600-ft) Stony Pass from Creede, CO, in an incredible journey retold years later by Louis Wyman. "Dad's daydreams were not the idle musings or the fantasies of a mystic," Wyman said. "They had a way of erupting into reality. He advocated and built good roads," he said. "During the summer of 1910, he was up to his sweatband in a project that took in half the state of Colorado. He envisioned an automobile highway, unheard of at that time, running southwest from Denver through the scenic grandeur of the high Colorado Rockies. The road would traverse a thousand miles or more of the state's finest recreational land finally circling back to Denver. Years later, when all of the county roads had been connected, it became known as 'Colorado's Thousand-Mile Circle Route.' Of course, Silverton and the San Juans were bright stars along the way."

Jan 1, 1997

By G. Camposano, J. Aponte, B. A. Ferguson

The paper covers mining operations and preparation of the ore prior to metallurgical treatment in the Process Plant. Mining operations are primarily concerned with the delivery to Ore Preparation of a balanced ore feed within fairly rigid specifications as to both ore type and chemical analysis. The mining method, systems of geological and engineering control, and the equipment employed are therefore reviewed in this context. In Part One of the paper the physical and geological characteristics of the orebodies, including the varied nature of the ore itself, are first described. Orebody evaluation, the calculation and classification of ore reserves, mining planning and forecasting to ensure continuity of production are covered, and the particular problems presented by sampling, the erratic distribution of ore values and the variation in the density of the ores are also mentioned. Mine design and ore excavation practice are described, together with the way in which they have evolved with recent developments in modern mining equipment. In Part Two of the paper, a detailed description of the Ore Preparation plant is given, centred around the concept of rubbling as a means of separation of the barren hard boulders from soft lateritic ore. Ore blending and ore reclamation operations are explained followed by a detailed description of the drying and crushing plant. The importance of the control of moisture content and ore sizing in the feed to the metallurgical plant is emphasized.

Jan 1, 1979

By F. Montgomery Lyon

Pyritic sulfur in coal occurs as discrete mineral particles, and its liberation and physical rejection is the primary target for coal desulfurization. An acceptable solution to the pyrite removal problem from fine coal is not found in the standard methods of coal cleaning such as jigging, heavy-medium separation, tabling, and hydro-cycloning. Although fine coal is an ideal size for froth flotation, this method, as currently practiced is also unsuitable as the fine pyrite usually floats with the coal. One possible solution to this problem may be the froth flotation of pyrite from coal. This reverse flotation scheme would have the major advantage of removing both free pyrite and locked pyrite-coal combinations. With this possibility in mind, we have, as a first step, compared the flotation and adsorption. characteristics of an ore-pyrite and coal-pyrite with potassium-ethyl-xanthate as a collector 1 Related Research. The action of ethyl-xanthate on coal has been studied 2 by Horsley. He measured the contact angles of coal in distilled water and in the presence of purified ethyl-xanthate. The results indicated that the xanthate was not adsorbed by the coal. Additional contact angle data were obtained to determine the effects of cupric, ferric, and ferrous salts on the system. Then either the ferric or cupric salts were in, solution with the xanthate, there was an increase in the natural contact angles of the coal. This indicated that these heavy metal ions activated the flotation of the coal with xanthate. However, ferrous iron did not act as an activator. Horsley stated that the most attractive explanation was that the xanthate is oxidized to dixanthogen in the presence of the ferric and cupric ions.

Jan 1, 1971

By David A. Gulley, William A. Vogely

INTRODUCTION The Scope of the Chapter This chapter discusses environmental regulation and closely-related public policies associated with mineral development in the United States. This chapter outlines the nature, extent, and amelioration of secondary effects of mineral development. It sketches the policy foundations of regulation; discusses the implementation of environmental law; describes land use conflicts and land management regimes; and surveys the costs and benefits of environmental regulation. Since regulations are subject to frequent change, the chapter emphasizes basic factual and conceptual material, rather than specific regulations. The goal is to familiarize the reader with the general nature of environmental impacts and mitigation which arise in the minerals industry, and with the issues surrounding the regulation debate. The chapter is organized as a series of sub- chapters. The first of these is a discussion of the conceptual foundations of regulatory policy. The second section summarizes the principal federal environmental statutes, and the implementation of such regulation. Following that, the third section summarizes the current state of knowledge regarding the types of environmental impacts associated with mineral development. This discussion, organized in a format similar to that used in environmental impact statements, can be thought of as a guide to reading and understanding such statements. Next, the fourth section surveys studies of the costs and benefits of environmental regulation. 'These empirical studies are evaluated in terms of the framework developed in the first section of the chapter. In the fifth section, the discussion turns to federal, state, and local approaches to land use control and siting, and the economic analysis of such conflicts. Included are discussions of the two principal forms of public lands mineral entry, the 1872 location patent system and the 1920 leasing approach. CONCEPTUAL FOUNDATIONS OF REGULATORY POLICY David A. Gulley The Role of Regulation in a Market Economy What is Regulation?: Regulation is the intervention of government in the activities of the private market. In a market society, the private sector is presumed to be the most appropriate economic agent. Given this presumption, regulation generally begins with a demonstration of persistent problems under laissez-faire in a given context. Environmental and related regulation occurs because the public believes the free market does not properly value environ- mental quality. In this section, concepts are advanced to aid the reader in understanding the government's role in this respect.

Jan 1, 1985

By H. Nakazawa, A. S. Malicsi, K. J. Reid, P. J. Ryan, I. Iwasaki, P. W. Weiblen

Precious metals are commonly believed to be recovered along with sulfide minerals in flotation, but a few neutron activation analyses showed that the recoveries of gold and silver were unexpectedly low. Reasons for low recoveries of platinum group metals remained unresolved due to interferences in the analyses. Electron microprobe, scanning electron microscope, and scanning Auger microprobe analyses have identified nickel arsenide minerals in the ore and confirmed a close association of platinum group metals with the arsenide minerals as minute inclusions. These results indicated a need for re-evaluation of flotation procedures that have so far ignored special problems related to arsenide minerals. The electrochemical and flotation behaviors of nickel arsenide and their application to the flotation recoveries of precious metals from copper-nickel bearing Duluth gabbro are presented.

Jan 1, 1987

By Julia R. Budden

The role of bacterial oxidation in the mining industry is becoming more widely accepted. Western Australia has accepted the technology as a pretreatment for refractory gold concentrates more readily than most. The third of such plants has been completed at the Y ouanmi Gold Mine. This is situated approxi­mately 500 kilometres north east of Perth, in the Yilgarn mineral field. Y ouanmi concentrates are produced from underground ore and contain arsenopyrite and pyrite as the main sulphide miner­als. Refractory gold from this deposit is generally associated with the arsenopyrite portion of the material. Gold Mines of Australia Ltd ("GMA") initiated pilot scale testing at the BacTech premises in November 1993. The decision by GMA to use BacTech's technology was announced in February 1994. Design and construction commenced at this time. Bacterial growth on site was initiated in July 1994 and continuous opera­tion began in the October. Concentrate was added at 0.5 tonnes per hour and this has increased to 1 tonne per hour.

Jan 1, 1995

By Andrew T. MacKenzie, Paul A. Rantala

Predictive pastefill rheology (flow characteristic), models have long challenged pastefill practitioners. While the methodology and practicality of recipe formulation is attainable in most locals, the remaining challenge has been to devise a predictive mathematical or empirical model of paste flow characteristics. Flow phenomenon can now be assigned mathematical and physical basis. The authors herein disclose physical and mathematical methods that demonstrate how operators could proceed when designing reliable pastefill systems. Knowledge presented will allow users flexibility in adjusting flow-rates. Laboratory data shows stiff pastefill delivery design can be derived through mathematical relationships of particle size, material characteristics and pipe diameter.

Jan 1, 2001

The authors give a corrected form of the Korobov algorithm of optimal open pit determination and describe a method of optimising the mining sequence within a preliminary pit design. A method of automatically including roadways is also given.

Jan 1, 1992

By Robert L. Bates

The natural separation of one element or compound from others in the earth's crust is a rare geological phenomenon; accumulation of large quantities of a separated substance forms mineral deposits of value. Although igneous and metamorphic processes are effective at times, by far the most significant fractionation is sedimentary. High-silica sandstone, high-purity limestone and dolomite, salt, and anhydrite-gypsum occur in very large deposits and are termed first-order fractionates. The marine diatomite of California, the trona of Wyoming, and the kaolin of Georgia and South Carolina are in deposits of comparable purity but smaller size, and are designated second-order fractionates. The paper considers the various processes and environments in which such industrially valuable deposits were formed.

Jan 1, 1972

By Jerry R. McGaha, Joseph A. Dos Santos

The favorable economics of conveyor based haulage, especially in moving large volumes. has long been acknowledged. This has given impetus to significant developments over the last two decades in conveying systems and equipment. Such developments have resulted in improved equipment and system reliability, versatility and mobility. The present writing presents conveyor systems and their variations. Long overland conveyors of various profile and plan layout are considered along with various typical support systems. This includes discussion of horizontally curving, two-way and booster driven conveyors. High Angle Conveyors-[HACs] are reviewed, citing in-pit as well as plant application. Finally, several important advances in idler and in pulley design are presented.

Jan 1, 1989

By Douglas W. Fuerstenau

Technological innovation is needed to meet the challenges that face the mineral industry because ores steadily become lower in grade, more complex in mineralogy, and must be processed in the face of ever- increasing environmental constraints and increased costs. How periodic innovation in mineral processing helped overcome the challenges that faced the mineral industry is briefly traced from antiquity up to the present time.

Jan 1, 1989

By C. M. Brown

Common operating philosophies and objectives of mining and mineral process operations are discussed. Key information required to effectively monitor operations is reviewed in conjunction with the impact of external variables such as commodity price changes on strategies adopted.

Jan 1, 1991

By Sheldon Shepherd

Fifty years ago, belt scales were mechanical devices based on a complex weight balancing design. Today's systems use load cells to assess material weight, belt speed sensors and microprocessor-based integrators to continuously compute the rate of material transferred along a conveyor. Belt scales have become important assets to a plant. They help maximize the use of raw materials, control inventories and aid in the manufacture of a consistent product. Choosing and installing a belt scale system may seem complicated but it can be simplified by following a few guidelines.

Jan 1, 1999

By David Wright, Colin Burns

Successful leaching of gold depends on appropriate chemical conditions; contact between leach solution and the gold particles; separation of the leach solution from the solids and extraction of the valuable ion from the solution. Irrespective of the leaching method employed the chemical conditions required are similar as is the dependence of solu­tion/gold contact on liberation. The various leaching methods available vary in the means by which gold/solution contact and solid/liquid separation are achieved. The essential difference between heap or vat leaching techniques and those involving agitation of a slurry is dependence on percolation for effective gold/solution contact. The most significant factor preventing uniform percolation is the presence of fines or clays. The quantity and character of the fines fraction is ore type dependent and may result from crushing, degradation during stacking or leaching, or the natural size distribution of the ore. The problems associated with fines can be aggravated during stacking and preparation of the heap. Segregation during stacking can result in concentration of fine particles at the centre of heaps. Further concentration of fines may also occur during irrigation by the movement of the fine particles with the solution. The end result is that the areas in which fines are concentrated become areas of low permeability. The contact between leach solution and the ore in such areas is, at best, slowed down dramatically and, in some cases, prevented altogether. The consequences of this phenomena are slow leaching and a reduction in recovery. The conventional solution to this problem is well known. Agglomeration of ore prior to heap leaching is practised widely. The effect of agglomeration is to immobilise the fines by causing them to adhere either to each other or to larger ore particles. The net effect is that the ore behaves as if no fines were present. The use of agglomeration is limited only by its cost, the most significant components of which are the cost of binding agent, commonly cement, and the capital cost of the agglomerating equipment.

Jan 1, 1995

By E. L. Bohnet

The purpose of this paper is to translate a mining company's "Corporate Objectives" into usable and practical guidelines for long term mine design and production scheduling. These guidelines are required to ensure that both operating and development properties are designed and economically ranked on the same basis, and with the "current" Corporate Objectives in mind. Secondly, if both management and mining engineers have a better understanding of the cause and effect of corporate policies, then penalties and risks associated with various Corporate Objectives can be put into better perspective for management. Corporate Objectives, relative to usable guidelines for either short and/or long term mine planning, could be defined as one or more of the following four objectives: 1) Maximize the recovery of the economic portion of the defined geologic resources, and hence, maximize total non-discounted project cash flows and profits (most common approach in mine design), 2) Maximize the Net Present Value (NPV) of the after-tax cash flows from each existing or proposed project, either on an individual basis or in concert with other projects, including downstream processing facilities (primary method used to judge relative investment merit of a proposed development or operating concept), 3) Limit short and long term capital expenditures to a defined ceiling, 4) Maximize product output for the existing facilities in the short term, or conversely, keep commodity production at a constant level for a series of years.

Jan 1, 1994

This chapter looks at the development and use of the operating budget. This is management's plan of action in the short term, usually one year. The operating budget includes all expensed production costs (i.e., all costs reported as cost of goods sold) but does not include expenditures on capital equipment, which are usually justified using discounted cash flow techniques.

Jan 1, 1999