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By Thomas L. Garwood, F. C. Menk

IT is generally accepted that no method of coal cleaning except froth flotation is effective in cleaning dust. In the majority of coals mined in the United States the dust sues contain a high percentage of impurities, hence the removal of the dust from the coarse sizes lowers the impurity content of these sizes. Dedusted coal is desired as a means of providing a better feed to cleaning plants because of increased efficiency in I both dry and wet plants. In dry-cleaning plants, a dedusted feed makes for a pervious and uniform bed. With a dusty feed the fines tend to segregate in the feed stream and pass en masse over the air separators, causing a lack of uniform aeration and fluidity of the bed necessary to efficient cleaning. In wet-cleaning plants dedusting of the feed often decreases the sludge problem to the point of eliminating the necessity of wasting wash water. It may be advantageous to eliminate sludge-settling equipment in favor of dedusting equipment, to provide the advantages of a dedusted feed to the wet-washing process. Dedusting advantages may include: (1) the removal of fusain, especially advantageous in plants washing coal intended for metallurgical coke; (2) prevention of the gradual build-up of solids in the wash water, with a consequent variation in the washing ability of the system; (3) prevention of the loss of dust to the sludge ponds, providing instead a fuel for local consumption or special markets. DEDUSTING The practice of dedusting, sometimes called aspirating, has presented a problem in disposing of the dust and intermediate small sizes recovered in the process. It has been found that no difficulty is experienced in disposing of the intermediate sizes, since they are free of fine dust and burn freely on grates built for small coal. They handle well, flowing freely from bins and hoppers and into conveyors, and pulverize easily. They have a low angle of repose. In tests made on this size as a feed to coke ovens, the results have been excellent, in that the natural breakdown of coal in handling and shooting in the mine gives this small-size coal good coking characteristics-producing a strong, fingery coke structure. Deduster dust from Illinois coal has been

Jan 1, 1950

By Paul Tyler

FULLY a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite,2 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines, It is largely a matter of mar-kets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal,"

Jan 1, 1938

By W. Tovote

This paper is based upon 12 years' experience in the Southwest, including three years that were spent in constant traveling as examining engineer for the Phelps-Dodge Corporation. The material was gathered during rather extensive work in Bisbee, Clifton-Morenci, Globe, and Tombstone, and also on short and rapid trips into most of the mining camps and prospect fields of New Mexico, Arizona, the desert country of California, and as much of Sonora as was safe at the time. My methods of observation and my deductions are not put forward as new or scientific; they are simply rough field methods, based upon short notes, rough sketches, and largely upon memory, which I have found useful for coördinating geological data for the purpose of passing quick judgment on mining possibilities in certain districts exhibiting uniform characteristics. The opportunities for observation have been better these last few years than ever before, due to the unprecedented activity in mining, which has caused the reopening of hundreds of old mines and the starting of even more numerous prospects all over the mining states. Possible Systems of Classification By Geological Provinces There are a number of well defined geological provinces in the territory under discussion, and a study of their individual features is of interest. The following are a few of those that are most striking in their uniformity. 1. The "Desert province," extending roughly from Wickenburg, Ariz., to and beyond Barstow, Cal. In its north-south extent it reaches up to the Colorado River and down into Sonora, but overlaps other provinces. It is characterized by a worn-down basement of schistose and granitic rocks, on which rest remnants of Paleozoic and pre-Paleozoic sediments, including very old limestones. The sediments are disrupted and contorted. Alteration in the mineralized areas is very prominent, especially in the schists and limestones. Cenozoic volcanic rocks, principally of semi-basic composition, have been intruded into this complex and sometimes cover it as lava flows. 2. The "Yavapai schist" province, similar to the one first mentioned, consists of metamorphosed basic and semi-basic rocks. It lies in northern

Jan 1, 1920

By E. L. Dougherty, J. W. Sheldon

A numerical method for computing the dynamical behavior of fluid- fluid interfaces is described. Results of studies made to assess the accuracy and economy of the method on a computer are reported. It is concluded that it is practical to obtain digital computer solutions for fluid- fluid interface problems with two space dimensions. PROBLEM DEFINITION We consider two-dimensional flow in a rectangle as shown in Fig. 1, where a fluid-fluid interface divides the rectangle into two regions. The pressure is specified along the lower boundary (the injection boundary) and upper boundary (the withdrawal boundary). There is to be no flow of fluid across the side boundaries, which are walls of symmetry for the flow, and px = 0 along these boundaries. The fluids are incompressible, the absolute permeability and porosity is constant, and each fluid has its own constant mobility. Thus, the pressure satisfies Laplace's equation in each region. Across the interface, pressure is continuous and the normal component of fluid flux is 1. These conditions are shown in Fig. 1. The velocity of a point on the interface in the direction of the normal from Fluid 1 into Fluid 2 is U,/ Q, where Un is the normal component of volumetric flux at the point on the interface, i.e., For brevity, we call the problem defined above "Problem A". Problem A is a simple example of a dynamical fluid-fluid interface problem. However, the same numerical methods which we use to solve Problem A can be extended to the solution of a large number of fluid-fluid interface problems which are mathematical models for various oil recovery processes,l hence our interest in Problem A. We define the interface by prescribing the x, y coordinates of a finite set of points. These points are called "interface mesh points" and are illustrated by triangles or asterisks in the figures. Fig. 2 is a procedural (flow) chart displaying the main steps in the solution. We comment briefly on some of these steps in this section and then give further details in subsequent sections. For mobility ratio greater than one it is well known that Problem A is unstable.*2 Small amplitude,

Jan 1, 1965

By R. Winand, M. Degrez, C. Temmerman

"The influence of the copper electro crystallization inhibitors (mainly thiourea, gelatin and chloride ions) is studied in a new fully automatic pilot plan. This paper describes the conception and the building of this plan. The new approach is to reproduce the experimental conditions observed in the industry with the three additives present simultaneously in the electrolyte and secondly to study the influence of a slight modification of the concentration of one inhibitor, the others being present in the electrolyte with their industrial nominalconcentrations.1. INTRODUCTIONDespite the fact that gelatine, thiourea and chloride ions have been used in copper electrorefining for a long time, precise knowledge concerning their influence on the cathode deposit, metallographic structure and associated properties is still lacking.Many authors studied the influence of each additive separately, or of two added at a time. Only a few authors studied the combined influence of the three additives added simultaneously. The general conclusion that can be drawn is that the combined influence is far from that forseen from the influence of each additive separately, or even from two additives used at a time. Moreover most of the experiments described in the literature were performed by adding all additives at once initially. It is however, well known that gelatine looses a great part of its activity during the first half hour due to degradation by sulfuric acid (as shown by the cathode overpotential drop). Thiourea is rapidly replaced by a number of degradation mole,cules and complex ions including cations from the solution, changing even the equilibrium between Cu, Cu(I) and Cu(II).Chloride ions are consumed by precipitation.A number of successive research projects [1-9] led pregressively to the concept that, in order to obtain reproducible results representative of industrial cathodes, it was necessary to simulate as far as possible industrial conditions. It was essential that all additives were added continuously during the electrolysis, with, as consequence, a continuous bleed.The purpose of this paper is to describe the concept of a new fully automatic pilot plan for copper electrorefining and to present the first results."

Jan 1, 1997

By Petrus van Staden, Dragan Milanovic, Francisco Sánchez, Eero Kolehmainen, Carlos Frias

"Currently there is no economical and viable process for on-site metal extraction from Low Grade, Complex or Poly-metallic deposits, and even more, there is not any industrial process or technology able to deal with polymetallic or bulk concentrates containing Cu+Zn+Pb base metals and also precious metals. Traditionally, metals recovery from polymetallic sulfide deposits is performed by mining, selective flotation to separate Cu, Pb and Zn concentrates, and finally, smelting/refining of those concentrates to obtain the refined metals. In many cases, selective flotation of that kind of complex ores produces low metals recovery and low concentrate quality containing impurities such as Hg, As, Bi, etc., which results in high penalties in treatment and refining charges, and consequently, worsening the economy of the mining business. Recovery of the valuable metals from Polymetallic, Complex or Low Grade ores could then be maximised by producing bulk concentrates or middling flotation products to feed novel hydrometallurgical processes, like the integral metallurgical system that is currently under development within the INTMET project. For example, producing bulk concentrates would increase more than 100% Cu+ Zn+Pb cumulative recovery versus conventional selective flotation. Founded by the Horizon-2020 EU Programme, the INTMET Project was started in February 2016 and will be running over three years. The INTMET consortium is led by Cobre Las Cruces (Spain) and integrates twelve partners from seven EU countries, and including Serbia and South Africa as well. The INTMET project represents a challenging opportunity to develop suitable technological solutions to deal efficiently with difficult, polymetallic and complex sulphide ores that are abundant in Europe and worldwide. Main activities carried out during the first 18 months of the INTMET project development includes: (i) An atmospheric leaching pilot plant having a capacity of 300 kg/h bulk concentrate which has been installed and operated continuously for nine months at the Las Cruces mine; (ii) Pressure leaching test work developed by Outotec; (iii) Bioleaching test work performed by Mintek in collaboration with MMI Bor. Prior test work was applied on bulk concentrate samples supplied from Spain, Portugal and Serbia. Some of the results of these technological developments have been very positive and are presented in this paper."

Jan 1, 2018

By John R. Freeman

The die pressing of brass may be described as a method of producing irregularly shaped parts of brass and other copper alloys by hot deformation in a die under pressure. Die pressing of brass was first developed as an improvement on sand castings in order to obtain irregularly shaped articles of brass with superior surfaces, a closer tolerance in dimensions, a denser structure, freedom from porosity and elimination of the relatively large amount of scrap invariably attached to sand castings. The freedom from sandy surfaces with consequent greater tool life in machining operations was also recognized as well as elimination of losses due to the uncovering of blowholes in machining operations. Die pressing also gave alloys of superior strength. Die pressings today are made from extruded rod or shapes, according to design of the part to be made. The greater number of pressings are made from round rod, because of its relatively lower cost and ease of handling. The rod is first sheared or sawed into desired lengths, the diameter of rod used and length of "slug" or "rivet" depending upon ultimate weight and shape of the die-pressed part to be made and design of die. The dimensions of the slug are figured so as to give the minimum amount of scrap to be sheared from the pressing as it comes from the die. Extruded shapes having I, T or X sections are often used when the finished part is to have a similar shape or heavy sections are joined by relatively light sections of considerable length. A rod bent in the shape of a U is also used on occasion, for similar reasons. Proper shearing of the slugs is of considerable importance. The sheared ends of the slugs should be as flat and straight as possible. Improperly sheared ends having an angle to the axis of the bar or a rough, uneven surface are liable to give folds or laps in the finished pressing and proportionately high rejections. The property of shearing varies considerably with different alloys and should be considered in the selection of a material for a given part. Where satisfactory shearing is not possible, the slugs may be cut from the bar by power saws. Extruded

Jan 1, 1931

By M. R. Todd, J. Szekely

THE mechanism of carbon oxidation in steelmaking processes has attracted considerable attention in recent years. The generally accepted model postulates that the reaction between carbon and oxygen occurs at the surface of CO bubbles that originate at the suitable nucleation points and subsequently rise through the metal bath.1-4 Although this model describes adequately the behavior of open-hearth type operations, it is not a satisfactory representation of carbon oxidation in oxygen steelmaking processes since it cannot account for either: i) the very high rate of oxidation per unit bath area,or ii) the commonly reported shapes of the curves showing the dependenie of the oxidation rate on the carbon concentration. The very high decarburization rates commonly encountered in oxygen steelmaking processes need no further elaboration; some typical plots of the rate of carbon removal against carbon concentration, taken from a publication by Li, Dukelow, and smith,' are reproduced in Fig. 1. It is seen from the curves that the decarburization tends to decrease from a peak or a plateau once the carbon concentration falls below a certain value; in the experiments reported, this critical value ranged from 1.2 to 0.2 wt pct C. The apparent dependence of the decarburization rate on the carbon concentration indicates that within this region phenomena associated with the transfer of car- bon must play an important if not predominant role. Since the concentration of oxygen in molten iron at steelmaking temperatures (removed from the immediate impact zone) is only about 0.1 wt pct,6 it is clear that simple simultaneous diffusion of carbon and oxygen to the surface of CO bubbles could not account for the rate of carbon transfer being the controlling step at carbon concentrations as high as 1.0 wt pct. The purpose of this communication is to present an alternative model which may explain at least qualitatively the apparent anomalies mentioned and may stimulate further experimental work. The Physical Model. It is suggested that the principal mechanism of decarburization is the reaction between CO bubbles and an emulsion consisting of molten iron and molten iron oxide particles in the vicinity of the "slag-metal interface9'.* This mech-

Jan 1, 1968

By Mafalda Arias

Most mining and mineral exploration companies? operate in remote locations, in Canada or internationally. Not knowing the cultural imprint of your team and the places where your company is active, may lead to problems. To set the foundation for a better world, it?s important to built trust and relationships inside your global team, within communities and together with stakeholders. Building the ?invisible asset? and developing intercultural awareness is an important part of leadership programs for geologists and engineers on your team, and should be a key component of your Corporate Social Responsibility initiatives. Why is culture important for mining and mineral corporations in their CSR initiatives? Because culture is the foundation of your organizational identity. Understanding the impact of identity, for an organization and for each individual, will provide a description of the experiences and values that affect every work placed interaction, with your clients, with colleagues, with suppliers, with the community of the host country. Each one of us sees and evaluates the world through our perceptions. Through these perceptions we give meaning; how we view and understand our reality which sets the tone for how relationships are built. This is what I call building the ?invisible asset?. Identity, experiences, values and beliefs are invisible commodities, locating them can be as difficult as finding a mine. But if they are not located, the commodity does not have value. Just like in the work we do in our industry. For example when you are working in an underground gold mine and the vein is lost, you keep on working and trying to find the vein; time passes, money is being used and no results. You decide to bring an expert on this type of deposits who gave you directions that allowed you to find the vein. To be a responsible citizen of the world and to set the foundation for a better world, it is imperative to go deep, as deep as your next drilling program, because only there and then, can you develop the cultural sensitivity and the ability to become an agent of change for responsible, sustainable and profitable businesses.

Oct 1, 2010

By S Strong, L I. Sanz Vivanco, T Brown

One of the most significant technical and practical challenges facing the tunnel construction team on the Legacy Way road tunnel project in Brisbane, Australia was how to erect the prestressed precast concrete slabs to form the smoke duct in the tunnel boring machine (TBM) tunnels.An essential part of the tunnel ventilation system, the smoke duct extends the full length of the 4.6 km-long twin two-lane tunnels. The vast majority of the tunnels (approximately 4.3 km) were constructed using two 12.4 m diameter double-shield TBMs. The refurbished Herrenknecht machines broke several world records on the way to completing the tunnel excavation works in just over nine months. With the excavation complete the focus turned to solving the complex civil tunnel fit-out challenges. A key component of the civil fit-out of the tunnels was constructing the smoke duct in the TBM tunnels, which was designed as a precast solution.The slabs, which each measure 8.62 m long × 2.0 m wide × 200 mm thick and weigh close to 9?t, need to be erected above cast in situ corbels whilst other tunnel finishing works continue. The space-proofing clearance offered by the design to the support corbels below and the precast segmental lining above was in the order of only 100 mm.This paper tells the story of how the Transcity Joint Venture (JV) tunnel fit-out team comprising some of Europe and Australia’s leading tunnel construction specialists drew upon the global strengths of the existing JV member companies and the global reach of leading TBM manufacturer Herrenknecht to develop an innovative system in solving this challenging problem. This globetrotting story, which starts in Australia, visits Europe and mainland China before returning to Brisbane where it all began.CITATION:Brown, T, Strong, S and Sanz Vivanco, L I, 2014. How the global experience and reach of tunnelling’s true multinationals helped solve a road tunnel fit-out challenge, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 507–512 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By L. D. Frink

THOSE actively interested in mining are fully aware of the ever-increasing difficulty of making conditions such that efficient work can be clone in underground openings, especially as higher rock temperatures are encountered in depth. This is also true where an effort is being made to cut down the burden of overhead expense by working headings 24 hr. in a day if blasting is done as often as is possible in that time. That the conditions resulting from both these causes have driven the native-born Americans from the mines and that their places have been taken by less efficient foreigners is a fact that we must all admit. The great war now being fought in Europe and the educational qualification clause written into our immigration law by the last Congress will probably limit very materially the supply of labor, such as we are now using in our mines, and will force upon mine operators the necessity of making this work appeal again to Americans. Metal tubing, with blower or exhaust fans, has long been used in supplying air to dead ends where natural ventilation is impossible, or in driving the smoke from such places, or in doing both, as the need might be. Here in Butte we have now come to use canvas tubing very extensively and find that it has many advantages not possessed by the metal. The use of flexible tubing is not new, but it has not been generally used in mining operations. Recent improvements, however, in the canvas itself and in the jointing of sections and manner of suspension have so increased its usefulness that it promises to add much to the efficiency of mining. There is now on the market a product that is impervious to air, is fireproof, and has a system of jointing which, permits it to be put up or taken clown in a few seconds. In this article an effort will be made to explain the manner in which canvas tubing is being used in the North Butte company's operations at Butte, Mont. The accompanying photographs will, I hope, help make clear what may be done with this material.

Jan 1, 1918

By R. A. Corley, W. R. Wilcox, J. R. Teviotdale

Chemical vapor deposition of hafnium carbide yielded whiskers, needles, dendrites, faceted crystals, and adherent coatings. The gas stream compositiom and the mass transfer conditions determined the habit of the deposit. The deposits were obtained at temperatures ranging from 1100" to 1800°C. HAFNIUM carbide has the highest melting point of any binary compound; therefore, its various potential applications are a subject of vital interest to the aerospace industry. The experiments described herein were performed to investigate the chemical vapor deposition of hafnium carbide with particular interest being placed upon the possible production of high-strength single-crystal whiskers for composite materials. In 1931 Moers 1 used a gaseous mixture of HfC14, Hz, and toluene to vapor deposit crystalline hafnium carbide on a tungsten filament heated to 2400°to 2800°C. More recently Lepie 2 deposited hafnium carbide on graphite using HfC14 and methane in a helium gas carrier. The pyrolytic depositions described here were accomplished in graphite tubes by using various gas mixtures and dopants. The resulting crystal habits included whiskers, needles, needle dendrites, bulbous dendrites, faceted crystals, and smooth, adherent poly-crystalline layers. EXPERIMENTAL The depositions were carried out in an induction-heated graphite tube, 1.2 cm ID, which was contained in a vertical 9-cm-ID quartz tube. (A more detailed account of the experimental procedures and results is given in Ref. 3.) Refractory oxide fiber and tubes and graphite felt were utilized jointly and singly for therma1 insulation. A typical temperature distribution is shown in Fig. 1. The reactant gases were introduced at the top and removed at the bottom of the tube. Table I summarizes the experimental conditions and results. Many deposition habits were obtained. X-ray analyses showed that they possessed the hafnium carbide structure. Almost invariably these formed well above the point of maximum temperature in the graphite tube. The habit depended strongly on the gas composition. In a series of runs (e.g., run A) using HfC14 and toluene in H 2, hafnium carbide coatings, Fig. 2, were reproducibly obtained at the position where the tube wall was 1400°C, and bulbous dendrites, Fig. 3, were

Jan 1, 1969

By Paul M. Tyler

FULLY a decade ago, demand for ground mica began to exceed supplies of scrap mica from manufacturing operations and of waste block from feldspar and sheet mica mining in the United States, with the result that in recent years the market has absorbed larger and larger quantities of mica recovered as a by-product from clay washing,1 as a joint product with kyanite12 and by grinding schists. So far, only schists that contain a large percentage of mica have been utilized for making ground mica, but already there has been a good deal of wishful thinking with regard to recovering mica as an aid to the prospective working of low-grade gold ores and ores of certain base metals. With wet-ground mica selling at $60 to $100 a ton and even dry-ground mica worth over $20 a ton, many ores that could not be considered as otherwise workable under present conditions will show commercial possibilities if they can be made to yield even a relatively small percentage of salable mica. An interesting paper might be written on the coming role of industrial minerals as joint products of metal mines. It is largely a matter of markets. Many years ago I watched the mess left behind the gold dredges in the mountains of Colorado and thought of the Denver sand and gravel operators who prided themselves upon their canniness in providing devices for catching gold merely as an incident to their regular business of selling what we miners classed as "tailings." Nowadays almost every milling or mining operation near settled communities finds use for at least part of its waste for road material or concrete aggregate and several eastern iron mines have gone into the crushed-stone business. Promoters now mention fertilizer "filler" as potentially salable at all the way from $1 to $10 a ton, or whatever is needed to cover costs of mining and treating the "ore" and leave the metal values as "clear profit." In emulating the pork packers in their efforts to utilize "everything but the squeal,"

Jan 1, 1938

By J Karlovšek, M Hafner, M Žibert

The transport network in Europe is probably one of the most important systems for the European economy and society. Trans-national transport routes play a vital role in the traffic of goods and the supply of the population. In this respect, critical road infrastructures, like bridges, tunnels or control centres, can have a bottleneck function. Any disturbance of these structures could lead to negative consequences for the population and the economy as a whole.Project SecMan – Security Manual – is a simple four-step procedure for the identification of critical road infrastructures; assessment of these infrastructures regarding various man-made threats and the determination of effective protection measures was developed. These methodologies are summarised and combined into a comprehensive best-practice manual that allows for a trans-national structured and holistic security-risk-management approach for owners and operators of road infrastructures in Europe.Currently no common processes, methodologies or standards exist in Europe regarding the consideration of security relevant events for critical road transport infrastructures, eg tunnels, control centres and bridges. Attacks on the former can have severe short- and long-term effects with high media attention. A trans-national risk management approach would increase the possibilities for prevention as well as mitigation. A trans-national emergency response strategy would increase preparedness, as well as facilitating and accelerating the reaction in the case of an event.The main objective of the project is to develop a practical process for the identification of critical road infrastructures based on generally accepted security aspects. The assessment of these infrastructures would be carried out in a structured and traceable way regarding security relevant risks and the determination of effective protection measures for prevention and mitigation.The project is implemented by the German Federal Highway Research Institute (BASt) together with project partners from Austria (ILF) and Slovenia (DARS, ELEA iC).CITATION:Hafner, M, Karlovšek, J and Žibert, M, 2014. Road infrastructure security assessment and measures selection methodology using secman – tunnel example, in Proceedings 15th Australasian Tunnelling Conference 2014 , pp 69–82 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 17, 2014

By A. H. Hand

When considering the question of future demand for crude petroleum in California, one must first decide whether it is to be approached in the light of the definition of "demand" when used in economics; i.e., "The quantity of any commodity required or sought in the market," or in the light of markets developed to dispose of total supply. Therefore, is the California demand of future years to be predicated on a continuation of supplying markets developed following the surplus production commencing in 1922, or predicated on supplying what would be termed economic markets ? If the latter, what are economic markets ? Obviously, the Pacific Coast States and Canada, Alaska, Hawaii and probably the Pacific side of Central and South America, can be considered as normal markets for California petroleum products. While there have been small quantities of gasoline shipped into the PacSc Coast from East Texas, transportation costs, plus import taxes in the case of foreign oil, are a sufficient barrier to justify considering that these markets will be retained. But how about our participation in Atlantic and Pacific foreign and intercoastal markets? During the five years preceding 1931 California shipped substantial quantities of gasoline to the United Kingdom and to France, Germany and Italy. During recent years our business in European markets has been restricted to occasional shipments of gasoline and Kettleman crude. This loss of business is occasioned by the development of production in the Mid-Continent, principally East Texas, and in Iraq, Rumania, Venezuela and other closer producing areas, which makes it impossible at the prevailing crude-oil prices for California to be competitive in supplying any substantial portion of these markets. It is therefore apparent that under a stabilized price structure that will return the California producer a reasonable price for his oil, future Atlantic foreign -business will be restricted to occasional spot cargo sales. As to Pacific foreign shipments which, in addition to Central and South America, consist principally of shipments to Japan, China, Australia and New Zealand: A considerable portion of the business we had with Australia and New Zealand until four or five years ago is now being

Jan 1, 1937

By Joseph A. Norden, A. R. Willson

Much has been written concerning the hoisting equipment of various mines throughout the country, but most of the literature on the subject, if not all, describes equipment of extraordinary capacity and the small and medium-sized outfits have been neglected. The hoisting equipment here described is capable of handling about 1200 tons per day. It has not been worked to capacity, but 600 to 700 tons, together with men and materials, have been handled in two shifts without any great effort. Only one shaft extends from the surface to the lowest levels of the mine; see Fig. I. It is composed of three compartments, two of which are used for hoisting, and the third for water, air, and electrical lines, and for sinking purposes. In 1909, this shaft was raised from the 1000-ft. (304-m.) level to the 700-ft. There a station was cut and an air hoist installed. At this time all mining operations were confined to the upper levels of the mine; that is, above the 700-ft. The ore was dropped to this level through chutes from the 300-, 400-, 500-, and 600-ft. levels and then lowered in cars on cages to the 1000-ft., which is the main haulage adit, the mill and railroad bins being about 3000 ft. from the shaft. Orebodies were, in due time, developed on the 1000-ft. level and below. Therefore, in 1913,the shaft was sunk to the 1150-ft. level and thereafter sinking was continued at regular intervals until the 1500-ft. level was reached. But, hoisting from the 1300-ft. level was a difficult and slow process with the antiquated air hoist, so, in 1916, it was decided to raise the shaft to the surface and install a modern, electrically operated hoist. This was completed early in 1917 and the hoist was in operation in March of that year. The Hoist Figs. 2, 3, and 4 show various features of the hoist and electrical equipment. A Nordberg engine of the double-drum, geared type, designed for a 10-ton load, including rope, at a speed of 1500 ft. per min., is used. The drums are 7 ft. (2.1 m.) in diameter, with a 54-in. (137-em.)

Jan 1, 1922

By A. L. Labbe

IT Is well known that the Cottrell process is more easily applied to certain kinds of smoke than to others. The successful Cottrell installations are those treating smokes that carry dust of a mechanical nature; also smoke carrying fume dust that contains an excess of sulfuric acid over that required to combine with the oxides in the dust. But up to the present time the process has not reached a satisfactory economical basis of operation, in the treatment of smoke' containing basic dust. It is not impossible to make a smoke containing basic dust suitable for the process by. humidifying or acidifying. A number of Cottrell plants use these two methods of conditioning smoke previous to Cottrell treatment, which are quite successful, but the use of either results in expensive operation and a substantial loss in metals.. For these reasons, I would say that the baghouse process has not been replaced by the Cottrell process in the treatment of smelter basic smoke. Basic smoke must be given a. preliminary conditioning treatment because the dust is not a conductor of electricity; the water or acid treatment imparts some conductivity to the dust.. The rate at which dust is recovered depends on the proportional amount of power transmitted to the, treater and on the rate at which the smoke passes through; therefore to maintain a maximum constant amount of power across the electrodes of the treater, the same degree of conductivity should prevail, at all times between the surface of the electrodes. For all practical purposes, in the application of this process to lead and copper-smelter smoke, we can consider that the conductivity of the gases is a .constant. The variations in temperature of the smoke have a much greater effect on the solids than on the gases; the only instance where the temperature of the gases plays an important part in the process is at plants using humidifying: The temperature does not affect the conductivity of mechanical dust because such dust has natural conductive properties. However, in the case of smoke carrying acid-fume dust, where the conductivity is imparted to the dust particles by coming into contact with the acid fumes, the temperature is of importance.

Jan 8, 1925

By Peter Johnson, David Barber, Lachlan Henderson

"The traditional approach to rail tunnel fire safety design is to follow NFPA 130, which assumes a major tunnel fire could occur and requires bi-directional emergency ventilation. There is no regard to the impact of ventilation on fire growth and smoke production. In Europe and other parts of the world, the need for tunnel ventilation systems to provide smoke management in the event of fire is being questioned. The European Commission’s Safety in Railway Tunnels TSI is based on a philosophy that improved running capability (preventing fires and other events stopping the train in the tunnel) and elevated fire performance of materials means the chances of a major fire in a tunnel is highly unlikely, with only small fires expected, and no tunnel ventilation required. This approach is reinforced by the International Tunneling Association which has recently published an Engineering Methodology for Performance Based Fire Safety Design on Underground Rail Systems, which includes a methodology that does not require assessment of tenability in tunnels, but requires a scenario based risk assessment to be undertaken to determine overall fire safety measures. Recent research by the University of Edinburgh has shown that forced airflow from a mechanical ventilation system may promote fire growth and increase smoke volumes much more than with natural ventilation. Whilst the concept of no mechanical ventilation (i.e. natural ventilation) is a new concept for some, for many rail tunnels it is worthy of serious further consideration. RAIL TUNNEL SMOKE MANAGEMENT AND STANDARDS Smoke management using mechanical bi-directional ventilation systems has been a central part of the fire safety design solution under NFPA 130 for rail tunnels since 1982. The current version of the standard, NFPA 130: 2014, states that mechanical ventilation should be fitted to rail tunnels of length greater than 305 meters and an engineering analysis should be undertaken for tunnels of length 61 to 305 meters to determine whether mechanical ventilation should be fitted. However, this approach is not necessarily reflected elsewhere in the world. In Europe in particular, mechanical ventilation systems for smoke control within rail tunnels have taken a much less central role within the standards framework."

Jan 1, 2016

By Theodore P. Holt

The Mines Operating Co.'s plant at Park City, Utah, was designed to treat the low-grade fillings in the old stopes of the Ontario mine. These fillings carry 6 to 14 oz. of silver, 1 to 2 lb. of copper, 0.01 to 0.015 oz. of gold, and a small percentage of lead and zinc. The treatment consists in mixing the crushed ore with coal dust and salt and then roasting in a new type of furnace by combustion of the contained fuel. The roasted ore is leached with an acid salt solution to dissolve the silver, gold, copper, and lead. At present these metals are precipitated together on scrap iron and the product sold to a refinery. The only new feature of importance in this scheme of treatment is the roasting process, which makes possible the chloridizing of ores without any loss of the valuable metals, and at a very low cost. History of the Development of the Process The roasting process- had its beginning in connection with research work at the Utah State School of Mines. N. C. Christensen, Jr., who held one of the School of Mines' fellowships, was engaged in some experimental work on blast roasting. At the same time I was doing some work on the insoluble gold in Mercur base ores. Mr. Christensen roasted some of this base gold ore in his pot furnace, and found that when he mixed a sufficiently low percentage of fuel with the ore, it did not sinter but roasted to a leachable product. We considered this a new application of blast roasting, and proceeded to test out a large number of ores in several different types of small roasters which we constructed.. This experimental work continued well into the summer of 1911. In August, 1911, the Consolidated Mercur Gold Mines Co. installed a small roaster of our design, which we proposed to operate on the counter-current principle, feeding mixed ore continuously on top, and at the same time drawing off the roasted ore from the bottom. By proper adjustment we hoped to maintain a permanent roasting zone near the center of the column, the ore moving downward as roasted. However, we

Jan 1, 1915

By L. A. White

IN this paper it is proposed to follow the developments in the design of the lead blast furnace at Port Pirie from the time The Broken Hill Associated Smelters Pty. assumed control in 1915 to the present time, with special reference to the development of the system using two superimposed rows of tuyeres as is now in operation. Lead smelting operations first commenced in 1889, when the British Broken Hill Pty. Ltd. started its first furnace. This was followed by installing two more furnaces during the same year and another the following year. In 1892, Broken Hill Proprietary Co. Ltd. acquired the smelting works and combined operations with those at Broken Hill, New South Wales; by 1897, the whole of the smelting operations had been transferred to Port Pirie and thirteen blast furnaces were built to treat the Broken Hill ore production. In 1915, The Broken Hill Associated Smelters Pty. Ltd. took over from the Broken Hill Proprietary and have carried out operations since that time. From its inception, the present company started on a long range program of reconstruction, in which the development of the lead blast furnace has played a prominent part. A definite trend in plant development has been towards the simplification of plant control by a reduction in the number of operating units. The great advantages of technical control which resulted from the very simplified flowsheet established in the continuous refining process stimulated the desire to extend the principle to the smelting operation. Thus in the sequence of furnaces described here, it will be noted that the trend has been towards larger and, of course, fewer units. With each such development it is significant that the operating conditions and metallurgical results have shown steady improvement. Standard Furnace In 1920 there were seven furnaces operating, five of a type subsequently called the standard furnace and two of the original thirteen smaller furnaces, the latter type being used for the treatment of drosses, etc. produced from the refinery section, while the standard type carried out the main, lead-smelting operations. The standard furnace (figs. 1 and 2) had the dimensions given in table I.

Jan 1, 1951