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By F T. Suorineni, L Baird, A Papaioanou, D Hines

The Mathews et al (1981) stability graph was developed to provide guidance in the determination of stope sizes to control dilution in bulk mining of large orebodies. Longhole and sublevel open stoping (LHOS and SLOS) are the lower end in scale of underground mass mining with panel and block caving (PBC) at the higher end. Currently, the stability states of stopes in the stability graph are described qualitatively as stable, unstable or cave. The alternative quantitative option to the qualitative stability graph is the Equivalent Linear Overbreak Slough (ELOS) stability graph. The ELOS stability graph only applies to narrow vein orebodies. It is easy for the Mathews et al (1981) and the ELOS stability graphs to be applied outside the limits of their databases. What is currently referred to as ‘stable’ in the present stability graphs has diverse interpretations at different mines depending on their acceptable dilution values. In 2014, a research program was conceptually conceived at the UNSW Australia School of Mining Engineering to develop a quantitative dilution-based stability graph independent of orebody width to address some industry concerns on the use of the stability graphs. A dilution-based stability graph provides the mining engineer the flexibility to determine open stope sizes based on what dilution amounts are acceptable. The graph also unifies both the Mathews et al (1981) and ELOS stability graphs for wide and narrow vein orebodies, thus, eliminating their potential misapplications. To date, the concept is proven with case studies from metalliferous underground mining operations located across Australia. This paper presents the dilution-based stability graph concept, the initial results and future plans to account for other critical factors and increase confidence in its application with the addition of more data outside Australia.CITATION:Suorineni, F T, Papaioanou, A, Baird, L and Hines, D, 2016. A dilution-based stability graph for open stope design, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 511–522 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By G. J. Simandl

"Since the 1980s, China has become the predominant producer of REEs. Recently, it introduced REE export quotas and this started a world-scale REE exploration rush. REE resources are concentrated in carbonatite-related deposits, peralkaline igneous rocks, pegmatites, REE ± P veins, ion adsorption clays, placers, and some deep ocean sediments. REEs could also be derived as a by-product of phosphate fertilizer, U processing, Ti-Zr-bearing placers, and exploitation of Olympic Dam-type sub-type of IOCG deposits. The ideal REE development target would be located in a politically stable jurisdiction such as Canada. REE grade and tonnage, mineralogy, and permissive metallurgy are some of the key technical factors that could be used to screen projects. INTRODUCTIONAccording to the International Union of Pure and Applied Chemistry (IUPAC), the term “rare earth elements” (REEs) encompasses yttrium (Y), scandium (Sc), and the lanthanide series: lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). This definition is used throughout this paper.REEs are subdivided into light (LREE) and heavy (HREE) categories. LREEs include, Sc, La, Ce, Pr, Nd, Sm, Eu, and Gd and HREE include Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y. Promethium (Pm) does not occur in nature. Concentrations of individual LREEs in the upper crust of the Earth are comparable to those of base metals. Even the least abundant REE (Lu) is about 200 times more abundant than gold.The production of REEs, reported in the form of oxides (REOs), for 2011 is estimated at 140 000 t (Figure 1a). Although high technology industries can substitute several REEs with other materials, these substitutes are typically more expensive or less effective than the REEs they replace. A number of countries, including the United States, consider several REEs essential for national security, their economy, and a general reduction in green house gas emissions. The forecasted demand for individual LREOs is much higher than that of HREOs (Figure 2). Dy, Eu, Tb, Nd, and Y are essential for the US economy and subject to predicted supply disruptions (U.S. Department of Energy, 2010)."

Jan 1, 2012

By Chris Larsen, Carole Fortin, Dave Scott, Curtis Deredin, Ian Orford, Jean Guy Gauthier, Andy Trusiak, Lyne Côté, Mike Cooper

"Upon successful commissioning of the Stage Grinding Project (Cormier et. al., 2002), process improvements predicted through pilot plant testing were obtained in several flotation circuits, resulting in higher grades and recoveries for zinc and lead concentrates. Subsequent to establishing new baseline operating conditions from the Stage Grind Project implementation, additional opportunities were identified, and through the application of Six Sigma methodologies further gains were made. Six Sigma improvement projects were carried out in the copper-lead, zinc, lead upgrading and bulk flotation circuits. The overall performance increase resulting from incremental improvement projects has been substantial.Most remarkably, given the operational maturity up to the late 1980’s, the Brunswick concentrator team has continued to deliver a steady stream of major improvements over the past fifteen years. While senior managers and their programs have changed several times, there have been some critical constants over the long run. Common elements have been a commitment to team work, a commitment to recruit and maintain technical personnel, a structured business improvement framework supported organizationally by senior management, and focus on a few priority initiatives rather than trying to fix everything at once.The paper briefly discusses the longer term setting and then endeavors to illustrate, with examples, how improvements are presently achieved by applying the Six Sigma quality program.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is one of the world’s larger lead/zinc mines. Milling of ore began in 1964 from the No. 12 orebody, with an expansion in 1966 to accommodate ore from the No. 6 mine. In excess of 100 million tonnes have been milled to date. The concentrator employs differential flotation to produce lead, zinc, copper, and lead/zinc bulk concentrates. The ore is massive sulphide, with approximately 20% valuable minerals, 60% pyrite and 20% silicates."

Jan 1, 2005

By B. Weyerman

U. S. Steel's Oak Grove Mine experienced several top hinge failures on their caving shields. It was determined that all the caving shields needed to be replaced with new caving shields before more thilures occurred. The cost and amount of time needed for several scenarios of caving shield change outs were compared. This paper discusses how Oak Grove Mine decided to and did change 126 caving shields in six specially designed jig stations underground during a longwall move using their own UMWA employees.

Jan 1, 2001

By R. L. Beatty

IN INDUSTRIAL and domestic daily life carbon monoxide is the most frequently encountered toxic gas. hazardous concentrations of carbon monoxide may be present in the vicinity of many industrial operations, such as metallurgical processes, coke ovens, and fuel- and synthesis-gas producers, and may be encountered in confined spaces, such as dwellings, garages, workshops, vehicular tunnels, and mining operations, in connection with the use of heaters, boilers, internal-combustion engines, after blasting operations, and after fires and explosions. Evaluation and control of the health and safety hazard caused by carbon monoxide depend primarily on the analytical detection of the presence of carbon monoxide and determination of its concentration in air and in various gaseous mixtures. The choice of method of analysis in any particular situation depends on such factors as required accuracy, range of concentration involved, convenience, speed of analysis required, quantity of sample available, qualitative composition of sample or atmosphere to be analyzed, and possible effects of interfering gases. Some of the methods described require only adequate understanding of operational techniques, whereas others require thorough appreciation and skill in applying the principles involved. The instruments and analytical procedures commonly used for detecting and determining carbon monoxide are described in detail, and reference is made to more specialized methods:

Jan 1, 1955

By G. B. Harris

It has long been appreciated that chloride chemistry has a number of advantages over the more traditional sulphate route for both extracting and separating metals. Modern materials of construction, coupled with the development of a more cost-effective and efficient hydrochloric acid regeneration technology mean that chloride-based processes are now more competitive and attractive. Such processing routes are able to recover more of the contained metal values in a feed, including iron in a benign and/or marketable form, and particularly the so-called rare and rare-earth elements which are increasing in demand in our electronic age. These factors, therefore, add appreciably both to the overall economics of a project, but also offer a much more sustainable approach to our dwindling natural resources. Additionally, chloride-based flowsheets can be much more environmentally-friendly, offering practical alternatives to two of the biggest headaches faced by the industry, namely cyanide usage and the generation of red muds. This paper presents a brief theoretical background, focusing on the latest developments of ferrous iron oxidation and the low-temperature, selective hydrochloric acid regeneration process, which is the key unit operation for any chloride flowsheet, and discusses in general the advantages of the chloride approach. Several recently-developed flowsheets, which have been tested at the miniplant level, are presented for gold, base metals, titaniferous magnetites and lead-silver ores wherein the advantages of considering a chloride approach are highlighted.

Jan 1, 2014

By D Laurence, L Ge

This paper demonstrates use of remotely sensed imagery in promoting sustainable mining. Remote sensing technology can be used during all phases of a mining project û from evaluating the resource, to making extraction more cost-effective, through to monitoring, mine closure and remediation. Use of the new generation of satellite platforms with the capability of acquiring satellite data with higher spectral and spatial resolution have the capability to emerge as essential indicator for sustainable development in the minerals industry. A life cycle approach to satellite imagery is discussed. The use of an imagery of the site prior to mining activity establishes the environmental baseline, guides mitigation measures and eventual help in suggesting remediation. Remote imagery provides the cost-effective means of monitoring reclamation, including the growth of planted vegetation, of the mine site and surrounding area. The latest advancements in satellite remote sensing are highlighted to meet the newer challenges of sustainable mining practices. Some of the worldwide successful remote sensing applications for the measurement and evaluation of the sustainable development impact of mining operations are described. Presently available source of imagery and its comparative advantages and disadvantages are provided as a guide. Finally, the limitations of this tool are indicated.

Jan 1, 2009

By R. W. Stahl

Employees and dollars are necessary to all enterprises and any force, such as fire, which destroys either, can bring very serious consequences, including business failure. Since everyone acknowledges the necessity of conserving human life, we will devote most of our paper to the economic factors involved. A coal-mine fire is considerably more difficult to combat than a fire in a surface building because of the combustible surroundings in the mine, the explosive gases emitted from the coal, the suspension of explosive dust when mine timbers burn and the unsupported roof falls, the limited space in which approach to the fire can be made, and the limited avenues of escape. A survey of coal-mine-fire protection indicated that a rather low value was being placed on property and equipment. This prompted comparison with other industries. The comments made in this comparison are not intended as an indictment of the coal industry, since we do have mines that are well protected against fire, but the comments on conditions at the mines visited are factual and may help others to improve similar conditions. SURVEY PROCEDURES Plants of the steel, aluminum, rubber, chemical, and petroleum industries were surveyed, and all facets of the fire-protection scheme were covered. The industrial plant invariably had four times as much water readily available for instant use than the mine. In many mines where water is available, no equipment for applying it is provided, such as hose, nozzles, and adapters, so that time is lost in collecting this equipment. (See Table I.) EXTINGUISHERS Many more and generally larger portable extinpishers are available at the plant as compared to the mine. The extinguishers are generally placed nearer to sources of danger. In addition, respiratory protective equipment is always available at strategic points in plants but only in a few mines. (See Figs. 1 and Table 11) INSPECTING AND TESTING EQUIPMENT Plant water facilities are checked weekly and flushed at 6-month intervals, and hose is pressure-tested at least yearly; some mines check water yearly, but hose is not tested unless used. Fire extinguishers are inspected weekly in plants and completely overhauled yearly; one mine had monthly checks and overhauls only after use. FIRE BRIGADES AND TRAINING Every plant had designated fire-fighters and some complete full-time brigades; at one mine a chief mechanic was designated as being in charge of fires, and other depended entirely upon officials who might not be familiar with the equipment. COST OF FIRES AND PERCENTAGE OF CAPITAL INVESTMENT IN FIRE PROTECTION The direct cost of recent mine fires ranged from $128,000 to $240,000; indirect costs, such as lost tonnage, idled equipment, lost orders, and the like might run the cost to over $500,000. (See Figs. 2 and 3).

Jan 1, 1961

The widely accepted kinetic model for the gaseous reduction of hematite is critically examined. The formation of the wustite layer during internal reduction cannot be explained in terms of solid-state diffusion. Present evidence indicates the existence of a micropore system in the wustite adjacent to the magnetite with the gas/solid type of reaction occurring not only at the iron/wustite interface but also at the wustite/magnetite interface. During the partial reduction of dense hematite pellets, in a controlled atmosphere, porous magnetite and wustite are formed as products. The mean pore size, as measured by mercury injection, increases with time at constant temperature and with temperature increase over the range 6500C to 950°C. The sizes of the pores indicate that Knudsen diffusion is the principal gaseous transport mechanism across thick layers of magnetite or wustite.The kinetics of the gaseous reduction to iron are consistent with a mixed control mechanism involving the interaction of gaseous diffusion effects with a first order reversible chemical reaction at the iron/wustite interface. Because of the larger pore sizes in the iron layers, ordinary molecular gaseous diffusion must be the principal transport mechanism. The usual experimental methods used for establishing the validity of chemical rate ~ontrol are incapable of differentiating between the mixed control- mechanism and exclusive chemical control.Some implications of mixed control kinetics are developed, including a predicted independence of rate on reducing gas pressure at higher pressures.INTRODUCTIONAn extensive literature review of the reduction of iron oxides has been compiled recently by Themelis and Gauvin (1962). From the large number of papers published and the widely divergent opinions of workers in this field, it appears that a simple unified quantitative analysis of reduction kinetics is not possible. The aim of the present paper is to show that a major cause of confusion is due to the attempts of many workers to interpret experimentally observed reaction rates in terms of a single rate controlling mechanism without due regard to other rate processes which must occur simultaneously.Some of the differences in behaviour reported for particles...

Jan 1, 1964

By Hal M. Lewers

IN the past few years and especially since the beginning of World War No. 2, gold has attained a new, important. and critical place in the international scene, and in world affairs. In the past, as far back as history records, most wars have been waged for the purpose of acquiring it from someone else by conquest. But now, the most titanic struggle of all time is being waged with the avowed purpose of not only destroying it, but of destroying all that it stands for and represents. A tradition dating back to ancient Rome, affirms that battles are fought by men with weapons, but wars arc eventually won by gold. The validity of that tradition is now being subjected to its major test. Hitler has proclaimed that in his new world order, the work dollar or reichsmark, a beautifully engraved paper currency representing only a theory of value, based on unit of work and production, will become the supreme medium of world exchange, and that gold eventually will he valueless and obsolete.

Jan 1, 1942

By J. Baird

The Sappington Bridge, a steel arch span bridge constructed in 1904 over the Meramec River, was demolished due to its advanced state of deterioration. The demolition was a project to benefit Crawford County, Missouri, the U.S. Army, the Missouri Department of Transportation, and the University of Missouri – Rolla (UMR) was conducted jointly by the UMR Rock Mechanics and Explosives Research Center (RMERC) and the UMR Center for Infrastructure Engineering Studies (CIES). By arrangement with Crawford County, a 55-foot span of the old bridge was brought to the University Structures Laboratory in Rolla, while the longer, 200-foot span of the bridge was demolished using preburning and explosives. Originally, the longer span was to be blown up by C Company of the 5th Engineer Battalion (from Ft. Leonard Wood, Missouri) under the supervision of personnel from UMR. Unfortunately, permission for the operation from the Department of the Army could not be obtained in time to meet permitting requirements for the demolition. Therefore, a commercial demolition contractor was employed to perform the demolition, and to remove the scrap.

Jan 1, 2003

By James Warner, Peggy Ganse, Glen Smoak, Raymond Henn, Sam Bandimere

Over the past several decades, cement-based grouts using ultrafine cement as are placement for portland cement have begun to gain acceptance as an alternative to chemical solution grouts, however the amount of information currently available on these grouts is limited. For this reason, the authors developed a field testing program to evaluate the penetration capabilities of various ultrafine cement grout mixes. The tests were conducted by injecting sand columns using different portland and ultrafine based grouts, the measuring penetration distances after applying equal injection pressure for the same time period. Results of tests performed in 1999 and 2000 are discussed herein.

Jan 1, 2001

By Jr .. Ebbley

The investigation of mine shafts and underground workings at Leadville, Colo., was started in May 1946 and recessed in November 3, 1946. Thirty-eight shafts and connecting accessible underground workings, comprising about a third of the accessible shafts in the district, were investigated. The Leadville district, a former important producer of lead and zinc, was considered by the Bureau of Mines to be capable of bolstering 'the waning domestic output of .these important metal. Accordingly, the investigation was initiated for the purpose of. .obtaining more definite data on sulfide and oxide reserves, evidence to justify completion of the Leadville drainage tunnel, representative large samples of the complex oxidized and mixed ores for testing to determine methods, beneficiation factual data to be supplied to property owners in order to stimulate production, and to determine the more favorable areas for development by the Bureau.

Jan 1, 1949

By McNicol M. D

Petroleum exploration in onshore Gippsland was directed in the 1950s and 1960s towards plays in the basal Latrobe and Strzelecki Groups, but these became forgotten in the 1970s with the Latrobe play discoveries offshore. The principal explorationists of the time were Woodside Oil and Arco Ltd, who then departed the scene after drilling some 18 wells without major success. In the late-1980s successful hydrocarbon finds in equivalent age Otway Group sediments in the Otway Basin were made and in early 1990 Tyers Petroleum began investigations into Strzelecki Group prospects as applied to the onshore Gippsland Basin. Some 18 anticlines have been mapped, based on shallower coal exploration drilling in the Latrobe Group, which from seismic and gravity evidence are believed to unconformably overlie similar anticlinal structures in the underlying Strzelecki Group. Strzelecki targets of interest within drilling depth are the basal Tyers Conglomerate/Rintouls Creek Sandstone Formations which outcrop in the north of the Latrobe Valley and are analogous to the Pretty Hill Sandstone in the Otway Basin. In addition, intra-Strzelecki Group targets similar to Heathfield and Windermere Sandstone Members are also considered to be present. Good source rocks are abundant including coal seams and carbonaceous sediments of Neocomian and Jurassic age, which lie within the oil window. Seal is provided by the overlying Aptian-Albian aged volcanogenic sediments. The Tyers/Rintouls sandstones - a target in the Woodside/Arco wells, with two exceptions, were not reached. Encouraging intra-Strzelecki shows were reported in many of the wells. Basal and intra-Strzelecki porous quartzose sandstones remain one of the few untested plays left in the Gippsland Basin and, in the onshore, merit extra attention as they he within the oil window at economically drillable depths.

Jan 1, 1992

By Gary Anderson

??Privately Held Corporation ??Incorporated in Delaware, May of 2002 ??HQ in Malvern, PA (just outside Philly) ??Approx 40 employees ?9 Field Engineers ?MSHA Certified ?10 Development/NOC Engineers ?Site Survey/Site Design ?RF Engineers ??Standards Based ?IEEE 802.11 ??Commercial Off the Shelf (COTS) ?Gateworks, Ubiquity, Atheros, Linux Based ??Technology was developed and inspired by the lack of communications during the terrorist attacks of Sept. 11, 2001

May 1, 2009

By Hidenori Hatta, Takero Watanabe, Hideo Yoshida

"The effect of the quenching rate on age hardening in an Al-6.0mass%Zn-0.75mass%Mg alloy sheet was investigated. The quenching rates and aging conditions were as follows: water quenching (WQ) or furnace cooling (FC) followed by pre-aging at 20°C,then artificial aging at 120, 160 or 200°Cwere performed. The peak strength of the FC and the WQ are very similarat120°C aging. It is important high strength was obtained even at the extremely slow quenching rate. On the other hand, the strength of the WQ significantly decreased compared to the FCat200°C aging. GP(I) zones were formed during the pre-aging at 20°C even if the cooling rate was very slow like the FC, and were transformed into the GP(II) ones at 70°C or higher and then into the ?’ phase. However, these zones were dissolved by reversion during heating to 200°C. Thus the strength of the WQ decreased. On the other hand, it is considered that an unknown cluster or GP zone with a thermal stability formed during the FC was not dissolved up to 200°C and was transformed into the ?’ phase. Therefore, a higher strength was obtained in the FC for the200°Caging.INTRODUCTIONAl-Zn-Mg alloys are widely available in commercial production because these alloy have lower quench sensitivity and can be produced by air cooling (AC). Heat treatable aluminum alloys are usually produced by water quenching (WQ) to increase their strength because a high cooling rate inhibits the precipitation of the stable phase during cooling and increases supersaturated solute atoms. However, Baba(1967)reported the strength of an Al-6%Zn-1.8%Mg(mass%) alloy without additional elements quenched by very slow cooling (15°C/min) was 96% of that quenched by WQ. Furthermore,the age hardening at room temperature (RT) occurs after annealing at 410°C followed by furnace cooling (FC, 0.5ºC/min or less)in these alloys. Therefore, the process of annealing at 410 to 430°C for 120 min followed by AC, and reheating at 230°C for 240 min, then cooling is recommended in the specifications (Japan Aluminum Association, 2011). Matsuda and Yoshida(1996)also recommended annealing at 300°C for Al-Zn-Mg alloy extruded products to inhibit age hardening at RT by precipitating the solute atoms and decreasing them in the matrix. It has been considered that the higher the content of excess quenched-in vacancy becomes by WQ, the higher aging rate at RT is obtained. Therefore,it is theoretically and commercially important to clarify the reason why the age hardening occurs relatively quickly in almost no excess quenched-in vacancies such as the FC, and why the same strength as the WQ can be obtained in the FC"

Jan 1, 2018

1. Domestic Production and Use: Twelve companies operated 31 primary aluminum reduction plants, three firms accounting for 66% of production. Washington, Oregon, and Montana accounted for 32% of the total production; Gulf Coast States, 25%; Northern States, 29%; and other Southern States, 14%. Output of primary metal in 1973 was valued at $2.2 billion. About 80% of the secondary recovery was from new aluminum base scrap and 20% was from old scrap. Aluminum consumption by 25,000 firms was centered in the East Central United States. Of aluminum consuming industries in 1972, building accounted for 28%; transportation 19%; electrical, 13%; packaging, 16%; and consumer durab1es, 10%.

Jan 1, 1974

This paper sets out to examine the possible relationships between three factors, they are, the rate of growth of world production of minerals, the growth of Australian production and the growth of scientific and engineering knowledge.The first two are quantified, in terms of tonnes and value. The third, an abstract concept "knowledge", requires to be quantified, in terms of manpower.A mathematical model, which has general application, was derived to demonstrate certain axiomatic premises and to define, more precisely, basic concepts related to the philosophy of knowledge.Finally a summary is made of education-cum-industry issues.

Jan 1, 1981

By Herbert H. Kellogg

The chemistry of sulfide roasting is analyzed to show those aspects of performance which Thecan be predicted from considerations of thermodynamic equilibrium. It is concluded that equilibrium calculations can serve as a yardstick for prediction of roaster-gas composition and sulfate formation in the calcine for fluid-bed roasting practice. A method of calculation which combines the equilibrium and stoichiometric factors is outlined, and illustrated by an example from the roasting of Cu-Fe sulfides. ON first examination the roasting of sulfides would not seem to be a process to which equilibrium calculations could be applied to yield results of practical value. The burning of sulfides is an ex-tremely spontaneous reaction, excess air is always used to obtain rapid reaction, and in most traditional roaster designs (hearth roasting) the temperature and gas composition vary widely from point to point in the roaster. These are all conditions which promote a non-equilibrium state in the roasting process. However, the introduction of the fluid-bed roaster1 has brought to roasting practice new conditions of operation, so that equilibrium calculations can be used to predict certain limited aspects of practical operation. The fluid bed is characterized by uniformity of temperature, gas composition, and calcine composition from point to point throughout the bed. These relatively uniform properties of the bed make the meaningful calculation of the equilibrium state of certain reactions in roasting possible. It is the purpose of this paper to analyze roasting from an equilibrium viewpoint, to show where the method may be expected to yield valuable information, where it fails, and to outline methods of calculation. Main Roasting Reaction The reaction MS (s) + 3/2 0, = MO (s) + SO, [I] might well be called the main roasting reaction. It adequately accounts for the well known facts that metal sulfide and air are the main reactants, and metal oxide and SO, the main products. Deviations from this simple stoichiometry will be discussed under side reactions. For all metal sulfides, Reaction 1 is strongly exothermic and the equilibrium position is far to the right. Since the reaction is exothermic, the equilibrium shifts in the right-to-left direction as the temperature is raised. However, at all practical roaster temperatures (between 500" and 1200°C), the amount of this shift is small, and the equilibrium position remains far to the right. The main roasting reaction is essentially irreversible, and the application of equilibrium considerations to this reaction will not be! a fruitful field of investigation. A knowledge of the rate of this reaction. although not the proper subject of this paper, is of great importance to the roasting process. Analysis of the factors which influence this rate shows that: 1) The rate will increase rapidly with increased temperature. 2) The rate will be proportional to the partial pressure of oxygen at the surface of the reacting particle. Because of diffusion effects, the partial pressure of oxygen at the particle surface may be considerably less than in the bulk of the roaster gas. For this reason, intimate contact between gas and solid and high relative velocity between gas and solid, such as can be obtained in a fluid bed or flash roaster, will markedly increase the rate of reaction. 3) The rate will be proportional to the surface area of metal sulfide. Therefore, smaller particle size will permit a more rapid rate per unit of weight. To achieve practical rates of roasting the partial pressure of oxygen in the roaster gases must be maintained at a finite level at all times. Even where the gas-solid contact is very good, as in the fluid-bed roaster, the oxygen content of the gas must not be allowed to drop below some limiting value (perhaps 1 pct), or the rate of the main roasting reaction will become too small for practical operation. Side Reactions in the Gas Phase The gas phase during roasting of metallic sulfides contains the elements oxygen, sulfur, nitrogen, by-

Jan 1, 1957

By J. W. Thompson

BURYING DEAD MINERS. BURYING BODIES OF DEAD MINERS. REVISED STATUTES (HURD) 1874, P. 263. SEC. 22. LIABILITY OF RAILROADS, ETC., FOR BURIAL EXPENSES.-When any railroad company, stage or any steamboat, propeller, or other vessel engaged in whole or in part in carrying passengers for hire, brings the dead body of any person into this State, or any person dies upon any railroad car or in such stage, steamboat, propeller or other vessel in this State, or any person is killed by cars, or machinery of any railroad company or by accident thereto or by accident to or upon any such stage, steamboat, propeller, or other vessel, or by accident to or in or about any mine, mill or manufactory,* the company or person owning or operating such cars, inachinery, stage, steamboat, propeller, or other vessel, mine, mill or manufactory shall be liable to pay the expenses of the coroner's inquest upon and burial of the deceased and the same may be recovered in the name of the County in any court of competent Jurisdiction. NOTE--The original Act of February 15, 1855 (Laws 1855, p. 170), makes no reference to the dead bodies of persons killed" by accident to, in or about any mine."

Jan 1, 1919