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By Oliver Bowles

"Asbestos" is not the name of a distinct mineral species but is rather a commercial term applied to fibrous varieties of several minerals. The origin and significance of names applied to asbestos by early writers are discussed in the section devoted to sources of supply and terms employed in ancient times. VARIETIES The most useful variety of asbestos is chrysotile, a fibrous serpentine the composition of which is expressed by the formula H4Mg3Si209. Chrysotile is characterized by a strength and flexibility that permit the use of the longer fibers for spinning. The bulk of the world production of both long and short fibers, is of this variety.

Jan 1, 1935

By H. G. Dwyer

CONSIDERATION for future expansion influenced the design of the new smelter at Chuquicamata. The section of the smelter now going into operation, while large, represents only little more than half of the ultimate plant. Equipment for the direct smelting of raw concentrates has been arranged in the conventional manner although needless details have been eliminated wherever possible while mechanical and electrical features not usually found in copper smelters have been incorporated. Access is afforded to all equipment but platforms and walkways have been held to a minimum. The poling and other platforms in the converter aisle, normally subjected to battering by ladles and other heavy equipment in transit, are of concrete construction with steel grid armor embedded in the exposed surfaces. Noticeably absent are the many platforms formerly required for the handling of converter flux since this material is charged to the converters through the side walls of the converter uptake hoods. Clear space with ample headroom is provided under each converter and converter puncher's platform to permit clean-up by small bulldozers. Remote controls have been introduced at many points. Electrical control rooms and control centers have been conveniently located. An electrical tunnel with cross tunnels and escapeways is situated under the entire length of the converter aisle for power feed lines. Skull breaking facilities are in a separate building near the smelter. A silica-slurry building with brick storage area is adjacent to the smelter building so that elevator service is available to both buildings. A smelter office, a change house and lunchroom are provided in convenient locations. Units of the smelter as presently constructed are shown in the plan and table on page 1194. The ultimate smelter will house 7 reverberatory furnaces, 14 waste-heat boilers, 9 Peirce Smith converters, 4 casting furnaces serving 2 casting wheels, and one holding furnace serving a straightline casting machine. Additional crane requirements in the converter aisle will necessitate the installation of special hoisting equipment in space already provided in a raised section of the roof over the casting end of the aisle. Thus a complete crane may be lifted high enough above the crane rails to permit the passing of another crane underneath thereby giving all cranes full use of repair facilities already installed. For the collection of gases, 2 dust chambers, each with separate stacks, will collect converter gases and 2 balloon flues with separate stacks will collect reverberatory furnace gases. Extensions necessary to complete the ultimate plant will be possible with little interruption to normal operations since the future converters and reverberatory furnaces will be added at the east end while additional casting facilities will be added at the west end of the present plant. The future units may be added singly or all at one time depending on requirements.

Jan 1, 1952

By Grieveson P, Terry B. S

Carbothermic reduction of sulphide minerals for achieving a selective separation of metallic species from complex minerals has been discussed by considering the prevailing oxygen potential during the course of reaction. Construction of univariant plots for the reduction of sulphides with carbon monoxide gas or carbon and in the presence of either lime or anhydrous calcium sulphate is the key feature of this work. The theoretical calculations for univariants in the Cu-Fe-S-O system indicated a preferential separation of metallic copper and iron by imposing a chemical potential. This is evident from a logarithmic plot of sulphur dioxide partial pressure against reciprocal temperature. The results are compared with empirical data for the reduction equilibrium. The reduction behaviour of the constituent sulphides are also discussed together with the experimental results and theoretically predicted phase stability diagrams.

Jan 1, 1992

By Robert L. Major

The expanded role which coal has been assigned in the energy future of the United States has raised numerous policy questions. The very complexity of these questions makes them suitable to analysis by econometric models. However, as the Wall Street Journal indicated in its recent article, business' success with such models have been mixed. I have been asked to present my views as to how coal producers can use such models and in what ways the industry is likely to be impacted by such models. I do not presume to speak for the whole coal industry, but only to share with you the personal observations of one who has worked "both sides of the street", having been employed' both by government and a consulting firm prior to joining the coal industry. In my opinion, the use of econometric models to analyze the coal industry will impact the coal producers in two main ways. First, their use by government will have a profound impact on future government policies related to the mining, transportation and utilization of coal. Second, such models, when properly calibrated and refined, may become useful tools for the coal producers in doing market research and long-range planning. While the former has already begun to impact on the operating environment or the coal industry, the latter is still in the embryo stage.

Jan 1, 1977

By Bernard Porter

The densities of LiF, NaF, and KF, of binary mixtures of these alkali fluorides, and of binary mixtures of UF4, ThF4, YF3, LaF3, and CeF with each of tie alkali fluorides were measured as functions of the melt composition and temperature. Molar volumes at 1,000° C were calculated for all the mixtures. Binary systems containing LiF exhibited molar volume ideality. Binary fluoride systems containing either NaF or KF as the alkali fluoride exhibit positive deviations from molar volume additivity. However, molar volumes in the NaF-KF system are ideal.

Jan 1, 1966

By A Mackay

As a result of the explosion in the 512 panel at the Moura No 2 mine in 1994 the role of the ventilation officer (VO) to submit sealing plans (on behalf of the operator/underground mine manager) has become one of the key duties of the VO of an underground coal mine in Australia. The intent of a sealing plan is to document the controls used to manage the build up of flammable concentrations of gases, and for these controls to be reviewed by the industry regulators. These sealing plans have brought a large amount of focus onto the sealing process and served the industry well. The legislation does not define sealing, or when it begins, but throughout the industry typically sealing plans are submitted 30 days prior to the last seal being constructed. This practice appears to have originated from the Moura 512 panel being a standing bord and pillar panel and where the explosive gas mixture could only occur after it was sealed. However, since the Moura disaster the industry has become dominated by goafing style longwall mining. Goafing panels differ from standing bord and pillar panels in that they typically have an unventilated goaf that can potentially contain an explosive mixture from start-up. This was recently highlighted by the explosion and fire on Longwall No 1 Tailgate at the Blakefield South Mine in 2011. The author ponders whether the industry should revisit sealing plans to focus on the core hazard and define that sealing begins when flammable concentrations of gases are created. Although defining when mine sealing begins is the key outcome of this paper, the main point is that VOs and industry regulators need to clearly understand what can occur in the atmosphere of underground coal mines. CITATION:Mackay, A, 2013. A case for change - Defining mine sealing and understanding flammable mixtures during sealing, in Proceedings The Australian Mine Ventilation Conference , pp 307-310 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By D. K. MACKAY

The production of oil and gas in Arkansas is confined to two distinct and widely separated regions of the state; namely: (1) South Arkansas in the Gulf coastal plain, where 49 fields-many containing two or more reservoirs or pools-yield oil, condensate and gas from beds in the Cretaceous and Jurassic, and (2) Northwest Arkansas, a part of the Arkansas Valley, where only dry gas is produced in 21 fields from sandstones of Pennsylvanian age. Exploration during the year 1945 centered largely in these two producing regions, but some of the geophysical surveys were made and wildcat drilling was done a considerable distance outside these regions.

Jan 1, 1946

By Daniela Bustinza

En el presente proyecto de investigación evalúa la posible reducción progresiva de acuíferos contaminados con uranio, mediante la estimulación de microorganismos reductores de metales disimiladores, los electrodos de estos organismos se comportan como donadores de electrones y de igual forma como aceptador de electrones que se llaman "electroquímicamente estimulantes” generalmente, estas bacterias reducen los minerales insolubles que contienen iones metálicos oxidados para poder generar energía. El organismo que se utiliza es el Geobacter este organismo puede desarrollar biobarreras permeables para la inmovilización de uranio a largo plazo.

Sep 30, 2022

By Ernst Lindemann

Steel suppliers are required to deliver sheets with particular qualities and with lightweight-potential to the automotive industry. New types of steel call for new production processes. SMS group has developed a new micro-mill-concept, the core of which is the belt caster. This was first built on an industrial scale and has been put into operation and developed together with Salzgitter Flachstahl GmbH. The robustness in industrial-scale operation could be verified. The full use of the belt casting technology, mainly related to energy efficiency and CO2 reduction, is realized with the micro-mill-concept. This is an in-line-process, casting and rolling in one line.

Aug 17, 2017

This manual provides instructions for installing, operating, and maintaining a protective canopy on the Joy Mfg. Co. shuttle car. These instructions are based upon actual installations made in the mine on two shuttle cars, model 21SC-2E. The parts list and engineering drawings for the protective canopy are included at the end of the manual. And a discussion of some alternative design concepts is also included. The manual can also be used for retrofitting other shuttle cars with similar protective canopies. Skilled mechanics can determine if the instructions hexein would he applicable to the other shuttle cars and can determine any necessary modifications if they are not.

Jan 1, 1973

By Rodolfo Lagos, Nicos Pfeiffer, Ben Harding, Clayton V. Deutsch

This paper outlines a cutting-edge probabilistic resource modeling workflow tailored to the Round Mountain epithermal gold deposit. The primary goal is to craft a robust and modern simulation process that enables the quantification and comprehension of anticipated discrepancies during mining reconciliation, offering a more precise gauge of expected gold quantities compared to conventional estimation models.

Dec 1, 2023

By Xiang Yu

Hong Kong has a dense distribution of utility services laid under its road network. Utility undertakers frequently demand road openings to install new services and/or maintain existing ones. Road openings can cause troubles to the road network and negatively impact the public interest. Highways Department is responsible for managing road openings in Hong Kong under the Land (Miscellaneous Provisions) Ordinance. Highways Department has spent a lot of efforts to computerize excavation permit processing and utility management. The computerized system has gone through several generations and the current one is called the excavation permit management system (XPMS). On the one hand, the XPMS handles various excavation permit processing functions including permit application/approval/refusal/issuance/extension/termination, fees/costs, permit conditions, and permit period assessment; on the other hand, the XPMS accounts for some important utility management issues such as spatial check, coordination of multiple openings, traffic management, audit inspection, and defect liability. This paper discusses how the application, coordination, and other administrations of an excavation permit are eased by using the XPMS in Hong Kong. Background information such as the governing legal and regulatory framework, and Highways Department?s administrative structure is introduced. The system architecture and advantages of the XPMS are presented. The work procedures and various functions of the XPMS are studied in detail.

Aug 1, 2013

By Elisa Comis, Jeffrey Peterson, Yama Ebrahimi

Construction of the Northeast Boundary Tunnel (NEBT), the last leg of the Anacostia River Tunnel System on DC Water’s Clean Rivers Project, started in September 2018 and was completed in April 2021. The 26-foot-bore earth pressure balance (EPB) tunnel boring machine (TBM) mined 26,737 feet at elevations between 80 to 160 feet belowground. Approximately 55% of the tunnel was cut through lower predominantly coarse-grained facies identified as the Cretaceous Patuxent Formation (undifferentiated) (PTX), and the remainder was cut through upper predominantly overconsolidated fine-grained plastic material facies identified as the Cretaceous Patapsco/Arundel Formation (P/A). Mixed face conditions were encountered in the transition from the P/A to the PTX and vice versa. This paper reviews the performance of the TBM that mined the NEBT through several unique challenges, including 8,000 feet of tunneling under the heavily developed Rhode Island Avenue corridor, major sensitive structures, cast iron water distribution mains, and other sensitive utilities.

Dec 1, 2022

By H. P. Hermance

Preliminary examinations of the Parker and Webb deposits were made by E. E. Maillott, Bureau of Mines engineer in July 1942. The chemical and spectrographic analyses included in this report wore made at the Eastern Experiment Station of the Bureau of Mines at College Park, Md., under the general supervision successively of S. M. Shelton and of Paul M. Tyler, formerly regional engineer, Eastern Region. Beneficiation tests were conducted under the supervision of Frank D. Lamb. The mineral exploration was under the general supervision of J. D. Bardill, formerly district engineer. Acknowledgment is gratefully made to the St. Joseph Lead Co., in particular to John S. Brown and P. J. Mechin for their assistance. Special acknowledgment is made to the American Metal Co., Ltd., ,Ind to T. C. Moore for furnishing core-drill and assay data; to the Universal Exploration Co. and P. B. Jennings; and to the Northern New York Mining Corp. and C. H. Sprague for their permission to publish the core-drill dta. Excellent cooperation was given by Dr. W; M. Agar and C, L. Rogers of the Geological Survey.

Jan 1, 1949

By A J. Broome

Since 2003, there has been an unprecedented growth in the demand for engineering, technical and project services in the mineral industries. This demand for services became evident in Australia earlier than many other markets and has since spread globally. This growth has created significant issues for the strategic direction and planning by the service provider. Such strategic questions include:- how fast to grow, how to recruit, train and integrate new staff, what market sectors to service, the selection of targeted customer sectors and managing strategic growth with short term demands and commercial reality. These factors are discussed using in depth experiences and examples that illustrate these strategic approaches. The relevance of this new industry environment to New Zealand services will be highly discussed.

Jan 1, 2007

By A E. Annels, I P. Hodkinson an, S P. Barr

Narrow vein systems represent an important source of gold, which have generally been exploited by small to medium sized companies. Their evaluation poses particular problems because of their grade and geological complexities. The determination of grade is arguably the most important activity in resource estimation, as it is generally grade and not tonnage that makes an orebody. This is particularly true of narrow vein-gold deposits whose resources are generally relatively small, though medium to high-grade (6 - 40+ g/t). They often display extreme grade anisotropy in all directions. Two grade populations are generally observed; 1) low, often subeconomic, background grades and 2) high-grades associated with discrete ore shoots. It is possible for gold to be distributed within the wallrocks as well as within the vein. Extremely high-grade values typify this style of mineralisation and require special consideration during grade estimation to determine if top cutting is valid or not. Estimation of both width and accumulation in 2D on vertical longitudinal projections or inclined planes have historically been used to evaluate narrow veins. Resource estimates based on traditional 2D methods is still widespread, but has in some cases been replaced by computer-based 3D modelling. Grade estimation methods are well-known, ranging from classical to geostatistical. Historically, classical methods such as inverse distance weighting have been used, though geostatistical indicator kriging methods are sometimes applicable. Geostatistical studies are driven by the production of reliable variograms, which in narrow gold veins is often problematic. It is generally difficult to define resources from drillhole intersections beyond the inferred and indicated categories with any confidence. In the majority of cases underground development is required to define measured resources and ore reserves. Trial mining/bulk sampling is often used to test estimated grades and also provides important data on ground conditions and the parameters relating to the proposed mining method required for ore reserve definition. Regular reconciliation should be undertaken between the estimated stope grades, grades indicated from stope/truck sampling and grades realised in the mill in order to determine whether correct evaluation strategies are being applied. The important feature of narrow vein-gold deposits is their strong geological controls; in response to this, geologists must understand the geology as best as possible.

Jan 1, 1999

By R. Hamar, G. Lamanthe

"To realize complex shaped pieces, like turbine blades, superalloys are cast with the lost-wax process. The end properties of these parts depend upon their microstructure as well as upon the occurence of casting defects such as micropores and hot tears. Such features are governed by the local solidification conditions which may be describe by the calculation of thermal transfers between alloy and mould. It needs the evaluation of numerous parameters which are fitted from experimental measurements in real castings. In further simulations, any parameter may be changed, in order to determine its influence. Such a single modification is quite impossible to realize in real castings, which shows that numerical modeling is a very good way to study casting processes.This modeling technique of casting is applied here to the real study of a typical low pressure turbine blade of a civil engine.IntroductionAircraft engine manufacturers use superalloys to produce turbine blades. They have to obtain a given microstructure and to avoid solidification defects to give good mechanical properties to theirs castings. For example, microporosity is induced by a large shrinkage that cannot be completely fed with the remaining liquid alloy .The optimization of casting processes needs a good Knowledge of the solidification process, that must be controlled at every place in the casting, and at every time of its freezing. Material and heat transfers that occur during the solidification, can be estimated from rather complex calculations. To model these physical phenomena, the evaluation of many parameters must be made. In this aim, some casting experiments are fitted with numerous thermal captors. The identification of experimental and computed thermograms let us estimate these parameters.A long-range scientific cooperation between SNECMA and INPG has enabled the realization of such studies on this topic. From all of them, this paper describes an experimental and computed investigation which has been led on a typical low pressure turbine blade of a civil engine."

Jan 1, 1986

By Olav Mellgren

Part I. The interaction between potassium ethyl xanthate and lead salts has been studied thermo-chemically. It is shown that ethyl xanthate reacts with lead carbonate, basic carbonate, thiosulfate and sulfate according to principles of simple chemistry, whereas reactions with lead sulfite, metasulfite, basic thiosulfate and hydroxide at high pH are associated with secondary reactions. A new compound "xanthogen thiosulfate" is postulated. Part 11. Adsorption of ethyl xanthate on galena has been studied quantitatively and thennochemi-cally. It is shown that an ion-exchange mechanism governs the adsorption process and that the heat of adsorption of xanthate on galena is equivalent to the heat of reaction of ethyl xanthate with bulk lead salts. It is concluded that the entropy content of the surface "compound" on galena is different from that of a corresponding bulk lead salt. Alkali depression is in part shown to be due to the instability of the xanthate-galena system at high pH and to the formation of basic lead salts. Sulfate and carbonate ions are shown to have a stabilizing effect on the xanthate-galena system. PARTI. THERMOCHEMISTRY OF ETHYL XANTHATE AND OF ITS REACTION WITH LEAD SALTS In the past little attention has been paid to the chemistry of lead xanthate. It is known that xan-thates form slightly soluble compounds with lead and that suspensions of lead xanthates in alkaline solution decompose rather readily.' The solubility of lead ethyl xanthate is of the order of 2.6 x 10-6 moles per 1. At increasing pH the xanthate concentration of a saturated solution contains more xanthate. Thus at pH 11 this xanthate content is about 100-fold larger than at pH 7.1 Xanthates are known to be consumed when added to a suspension of slightly soluble lead salts such as lead sulfate and lead carbonate. It is unknown to what extent this xanthate consumption is due to a simple chemical reaction because, frequently, observations are made which reveal secondary reaction products in such reactions. Thermochemical study of the reaction between xanthate and lead salts offers a means to clarify the significance of these reactions as the enthalpy changes can be accurately predicted from heat of formation of lead salts in pure solution reactions. In the present work the heats of formation of lead ethyl xanthate from potassium ethyl xanthate and lead salts are determined and some thermochemical aspects of xanthate in solution are studied. The results of these investigations are presented in Part I. In Part II the heat of adsorption of ethyl xanthate on galena surfaces is presented. All enthalpy changes were measured directly in a microcalorimeter. Calorimeter: The calorimeter used for measuring enthalpy changes was similar to that used by Redinha and Kitchener2 which was based on a description by Derbyshire and Marshall.3 Other useful references4,5 are listed. A sketch of the calorimeter

Jan 1, 1967

By G. Brooks, J. Naser, M. A. Sattar

CFD models have been developed and numerical simulations have been carried out to predict the formation of foam in oxygen steelmaking. Foam was considered as a separate phase comprising a mixture of gas and liquid. Bubble break up and coalescence models have also been incorporated in a CFD model to predict the number density of individual bubble classes. A population balance equation was used to track the number density of each bubble class. Decarburization with heat generation from chemical reactions was integrated in the process. User subroutines were written in FORTRAN to incorporate the foam formation, the bubble break up and coalescence rate and decarburisation in the main program. The model predicted the foam height, bubble number density, velocity of phases, decarburization, and turbulence. The result from the model has been compared with available data from literature and found to be in reasonable agreement with the experimental and plant data.

Jan 1, 2014

By I. D. Shah

A roasting procedure for synthetic copper sulfide which results in a reproducible transient melting at 450° and 470°C is described in this paper. Possible causes for this melting phenomenon are suggested, and also a procedure to avoid it during the roasting. This melting is believed to be responsible for the occasional occurrence of stickiness in the commercial roasting of copper sulfide concentrate. Many workers have studied the roasting of copper sulfides, but only Lewis et al. have reported that fusion and, in some cases, fusion with "boiling" occurred in the neighborhood of 450°C. The DTA and TGA apparatus, the materials used in this investigation, and the discussion of chemical reactions occurring during the CuS roasting are described in an earlier publication. CuS, in the form of either pellet or powder, was heated at 280° to 330°C in a flowing air or 30% 02: 70% N2 atmosphere. Heating was continued at this temperature until no further weight increase due to sulfates formation was observed on the TGA thermogram. This is believed to be due to the inability of SO, to diffuse out from the sulfate layer on the surface of the pellet, thus halting the sulfate-forming reactions. Hereafter, the sample oxidized in this manner will be referred to as "partially oxidized CuS." X-ray analysis and microscopic examination of a polished cross section of a partially oxidized CuS pellet showed the following order of layers starting from the center of the pellet: Cu2S, Cu2O, CuO • CUSO4, and CuSO4. A bare thermocouple inserted in the center of a partially oxidized CuS pellet (2.5 g) did not indicate any noticeable change in the temperature of the pellet when melted at 450° to 470°C in an inert or oxidizing atmosphere. During the preparation of a partially oxidized pellet, the temperature of a CuS pellet increased by 50°C due to the exothermic formation of sulfates in air at 320°C. The endothermic peak associated with the melting phenomenon at 450°C is shown in [Fig. 1.] A CuS pellet (0.2 g) was oxidized in flowing air (150 cc per min) at 10°C per min up to 320°C and held there for about 2 hr. Then, N2 replaced air and heating was continued up to 500°C. The exothermic peak at 320°C represents an overall formation of sulfates, and an endothermic peak at 450° to 470°C represents the melting phenomenon. To observe the melting visually, a small (50 mg), partially oxidized CuS pellet was heated (in static air) in a hot-stage microscope. The melting phenomenon was observed on an auxiliary TV screen. The sample

Jan 1, 1976