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By Vance G. Leak

A technique for recovering copper and steel from metallic scrap has been developed by the Bureau of Mines based on preferential melting in molten salt baths at 1,150° to 1,250° C, The molten salt, preferably barium chloride or calcium chloride, both minimizes oxidation of the metals and promotes heat transfer. Cleanest separations (0.01 percent copper remaining in iron) have been achieved by pretreatment (dipping or spraying) with sodium sulphate or sodium silicate, which alters and coats the surface of the iron to inhibit the alloying or brazing with copper. An economic evaluation of the process was carried out on six combinations of sweating media and inhibiting reagents. On the basis of the postulated model, a cost of about $0.20 per pound of copper recovered has been determined for the sweating treatment operation.

Jan 1, 1973

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 K. G. Tshilombo

It should be possible to use an oxygen probe to follow iron removal during converting, if local equilibrium is established between iron in the matte and the iron oxides in the fayalitic slag. The oxygen activity is expected to increase strongly as the iron content of the matte decreases (and the iron activity in the matte drops) while the iron oxide activity in the slag remains constant. To test this idea, oxygen activities were measured in synthetic mattes (made up of mixtures of Cu2S, FeS and Ni3S2) when in contact with silica saturated SiO2-FeO slags, and silica and (initially) magnetite saturated SiO2-FeO-Fe3O4slags. The measurements were performed on laboratory scale at 1250°C, using an oxygen probe consisting of an MgO-stabilized zirconia electrolyte and Fe/FeO reference, and containing the sample in a silica crucible. Electrical contact to the matte was by means of a platinum wire. The measured oxygen activity was sensitive to the iron content of the matte, and insensitive to the composition of the gas atmosphere over the melt. The measured oxygen activity was generally close to that predicted by Fact Sage calculations. This indicates that such oxygen activity measurements could be useful to monitor iron removal during converting of nickel-copper-iron mattes.

Jan 1, 2007

By Hakan Gurgenli

Many coal seams have weak shale immediate roofs that cause ground control problems. Therefore, it is important to know the properties of these shales so that preventive measures can be developed in advance. However, it is sometimes hard to understand this rock type due to its unpredictable behavior. A good example of this situation is found in two shale coal mine roofs located in the Illinois coal basin (Herrin No. 6 seam). Although, these mines are located very close to each other, one of them has many roof falls, whereas the other has no measurable ground control problems. The aim of this paper is to explain why and how one shale roof behaves worse than the other. Laboratory tests, including point load strength index, slake durability index, moisture activity index, weatherability index, water content determination, swelling strain and x-ray diffraction tests were performed to analyze the shale properties. According to these analyses, some useful correlations were found between the engineering properties, moisture-sensitivity indices, and weathering properties. Finally, mine and support design considerations based on the test results were discussed and recommendations to prevent ground control problems were given.

Jan 1, 2006

By Eric H. Brown

One of the best methods by which the results of accident-prevention work can be measured for any particular period is to keep an accurate record of the accident experience, which may then also be compared with the experience of others. The purpose of this report is to compare records of the salt-mining companies operating in Louisiana, and their assistance in making available their accident records is gratefully acknowledged. PRODUCTION Four companies produce salt in Louisiana -Avery Salt Co., Avery Island; Jefferson Island Salt Mining Co., Jefferson Island; Myles Salt Co., Weeks; and Carey Salt Co., Winnfield. Three of these companies operate within 30 miles of each other in the southern part of the State, and the other operates in the central part.

Jan 1, 1938

The National Institute for Occupational Safety and Health (NIOSH), in partnership with stakeholders in the mining and surface drilling industries, con-ducted research to develop engineering control technologies that reduce workplace noise exposure. The result of this research partnership is the development of a partial cab.

Jan 8, 2007

By D. N. Dietz

Jan 1, 1969

By Frederic Vanderoost

Actualmente, el manejo adecuado de las informaciones geológicas en el sector minero optimiza recursos y maximiza resultados. En ese sentido, el presente texto señala la implantación de un conjunto de herramientas para la administración de banco de datos geológicos, de forma corporativa y manteniendo un informe central de datos. Dichas herramientas se basan en sistemas comerciales de base de datos como Oracle, Microsoft SQL Server y Sybase, los cuales garantizan agilidad, flexibilidad y capacidad de almacenamiento para el manejo de informaciones adecuadas y las operaciones típicas de la industria minera. Asimismo, se presenta estudios de casos, analizando sus ventajas, limitaciones y dificultades encontradas en una mina.

Aug 25, 2002

Ultrasonic Extinction for High Resolution Particle Size and Concentration Analysis

Sep 13, 2010

By F. Habashi

The phosphate fertilizer industry is at present based mainly on the use of sulfuric acid. This technology results in the generation of large amounts of radioactive gypsum that represents disposal and environmental problems. Also it involves the use of expensive reactors for acidification that necessitates the frequent replacing the damaged agitators. Applying hydrometallurgical techniques such as in-situ, heap, or vat leaching to phosphate processing could solve these problems. In this case, however, nitric acid must be used and dicalcium phosphate (40% P2O5) may be obtained as a final product. It is insoluble in water but soluble in citric acid and is an excellent fertilizer. This technology does not interfere with uranium recovery if desired. In addition it permits the recovery of rare earths which are otherwise lost in the gypsum.

Jan 1, 2011

By John A. Herbst, Alexander Potapov, Xiangjun Qiu

"High Fidelity Simulation is a name applied to the use of first principles modeling tools including Discrete Element Modeling (DEM), Computational Fluid Dynamics (CFD) and Discrete Grain Breakage (DGB) to mathematically describe and study processing systems. Over the past few years, significant advances have been made in High Fidelity Simulation applications, particularly as many mineral processors have been drawn to the study and use of DEM of grinding mills for optimization purposes. This presentation provides an introduction to High Fidelity Simulation, with an emphasis on DEM. It will include insights into current applications of these tools including the optimal design (wear and throughput) of mill lining systems and media selection, the analysis and design (flow and efficiency) of the back-end of grate discharge mills. Advantages of full mill simulations versus individual sub-process simulations will be demonstrated for a SAG mill with different discharge system designs.INTRODUCTIONHigh Fidelity Simulation is providing mineral processors with the opportunity to analyze the behavior of mineral processing equipment from a fundamental or microscale point of view. In the past complex phenomena such as tumbling mill grinding had to be analyzed using black box tools such as residence time distributions for transport and classification functions for passage of particles through grates; while breakage had to be analyzed using PBM models who derived their form from theory but required direct measurement of kinetics. Today with the help of DEM, CFD and DGB these can be analyzed at a very fundamental level.The key element of DEM simulation is the application of Newton’s laws of motion to individual objects or discrete elements. Using this simulation method one can describe the position, velocity (both translational and rotational) of all objects and the transfer of momentum to other objects (Mishra and Rajamani, 1992; Cleary, 1998; Nordell et al, 2001)."

Jan 1, 2003

By John C. Machisak

STATISTICAL data on injuries and employment pertinent to metal mines and to their mills, and/or processing plants are presented in this Information Circular for the calendar year 1960. The information pertains to metal mines, as well as ore-dressing plants and primary nonferrous smelters, refineries and reduction plants, and their auxiliary works. These data are voluntarily submitted annually to the Bureau of Mines by the operators, and contribute greatly toward the promotion of safety in the mineral industries. The data presented are classified according to the principal mineral produced and include information on copper, iron, lead-zinc, gold-silver lode, gold placer, uranium-vanadium and miscellaneous metals. A breakdown of miscellaneous metals by commodities is shown in table 19, page 41. The data also relate to workers engaged in production, exploration, development, construction, and maintenance and repair work, as well as supervisory personnel and office-workers at the mine or plant site. Injury and employment data at metal mines and metallurgical plants in the United States for 1960 are shown under the following general sections: 1. General injury experience: Tables I-5-Data on injuries, injury-frequency and severity rates and related employment data, work location, and degree of injury.

Jan 1, 1963

By Kenneth Gavin

The accurate prediction of the shaft capacity of drives piles in sand continues to present problems for foundation designers. Research in this field has been carried out for many years and has yielded a wide range of design approaches -some of which have been shown by recent experimental work to be based on questionable assumptions. This Paper reviews some of the current popular design methods for piles in sand in the context of recent information obtained from high quality field tests conducted by institutions such as Imperial College London. A database of driven piles in cohesionless soils has been compiled from well documented (and reliable) case histories that have been reported in the literature. The measured shaft capacities of the piles in this database are compared with predictions made by the various methods and an assessment is made of the predictive performance and reliability of each method

Jan 1, 1996

Fossil fuel consumption in the United States increased markedly over recent years, and future demands expect to be even greater. Coal, this Nation's most plentiful natural fossil fuel, will play a key role in fulfilling these demands. With expectations of increased coal exploitation, the U. S. Bureau of Mines authorized this project, the objectives of whi.ch were to prepare an authoritative report on current surface coal mining technology, to define current problems and possible solutions, and to project future developments necessary to assure adequate surfaced mined coal production to meet the Nation's future energy needs. These objectives we're accomplished by an extensive review of available published literature and data gathering field visits to active surface coal mines throughout the country.

Jan 1, 1975

By Dennis R. Dolinar

Controlling coal mine roofs subjected to high-horizontal stress conditions has always been difficult and uncertain. Traditional supports such as wooden cribs and posts, concrete donut cribs, and standing supports collapse and fail when the roof and floor move horizontally as mining progresses. The former U.S. Bureau of Mines (USBM) (currently the U.S. Department of Energy (DOE)), in cooperation with Western Fuels-Utah, Incorporated, conducted research to provide an alternative for traditional secondary support systems in a 3-entry gate road system subjected to high horizontal movements. The support system used in several other coal mine operations, consisted of internal high-strength galvanized resin-grouted cable supports. The system virtually eliminates the necessity for external crib, timber, or concrete supports. The support system consisted of 2.4 m (8 ft) full-column resin grouted bolts and 4.8 m (16 ft) long cable supports installed in conjunction with wire mesh and "Monster-Mats." Cable loading and roof deformations were monitored to evaluate the behavior of the immediate and main roofs during first and second panel extractions. Additionally, cable trusses were installed on the longwall headgate to protect the coal conveyance system from roof and pillar falls created by the formation of cutters and gutters. The test results indicated that the designed support system successfully maintained the roof during the extraction of two longwall panels and dramatically reduced the cost of secondary support. This paper describes the theory of high-horizontal roof movements, the advantages of vertical cable supports and cable trusses, and presents the roof and cable measurements made to assess the support performance during longwall retreat mining.

Jan 1, 1996

By Ray Brainard

Charleston Water System?s Daniel Island Extension Tunnel, initially thought to be the simplest of the four replacement tunnels to design and build, became the most challenging after the discovery of an unexpected 30-ft thick lens of sand in the normally consistent Cooper Marl while sinking a shaft on Daniel Island. This paper will explore the challenges involved with determining the extent of the unforeseen lens of sand, the accelerated boring program, and the redesign of the vertical alignment?keeping the alignment between the sand layer and the bottom of the Cooper River. It will describe how the challenges were overcome, and how the Owner, Engineer, and Contractor were able to team together to achieve the desired results.

By G. M. Cresswell

The 2 360 t/h two module Phola coal preparation plant represents anew era of large plant in the Witbank coalfield designed to extend its life to 2020 and beyond. The plant uses the optimum processing model for Witbank coals, receiving a feed coal size of -50 mm, wet screening it into coarse and small coal fractions 50 x12 and 12 x0.63 mm before processing them in parallel through two primary DM cyclone sections, in order to make a 27.5 MJ/kg export floats product. The sinks are processed through a common high density DM cyclone section to produce a 21.5?23 MJ/kg thermal coal middlings product. The plant design incorporates the largest size DMS equipment used to date in South African coal preparation plants, i.e. 1 150 mm large diameter pump fed DM cyclones and 4.2 m width banana screens. The fine coal is conventionally processed by spirals, whereas the raw coal slimes are filtered using automated plate and frame filter presses and added to either the middlings or discards depending on its quality. The paper describes the database, innovative design concepts, construction, and commissioning.

Jan 1, 2010

By Axel Preusse

On the basis of the Law on Financing Hard Coal Mining dated 28 December 2007, the subsidized German hard coal mining industry will be shut down to the end of the year 2018 in a socially acceptable manner; in 2012 this decision will be reassessed. Even after the abandonment of all mining activities subsequent burdens are inevitable. In this paper, the possible long-term effects resulting from a mining industry history, which is spanning more than 200 years, and their possible consequences are pointed out, in particular in connection with the abandonment of mine water drainage measures which is economically meaningful in the long term. According to the decision situation as it presents itself today, this point in time will be far beyond 2018. In preparation for this, an action framework is to be developed in areas possibly affected.

Jan 1, 2008

By Jarek Jakubec

The new euphoria in diamond exploration brings with it a need to understand the challenges that new projects can face in different stages of the development and risks that the commercial outcomes from the new projects fall short of expectations. In many cases, the problems are related to a poor understanding of the technical risks and a failure to adequately address them during the course of investigation. Failure to evaluate all disciplines to the same level of certainty could lead to a situation where the important issues are only identified late in the project development, resulting in costly delays and financial difficulties. The diamond projects located in Canadian Arctic, with its challenging environmental, geographical, social, political and geological contexts are especially sensitive to the high variability of the outcome. This presentation highlights some of the technical aspects that could be the leading sources of risk in diamond projects and could ultimately result in inappropriate mine designs, reducing the economic outcome.

May 1, 2006

The design/optimization of the pump and cyclones to maximize grinding circuit efficiency first requires a concise understanding of, and clearly defined specifications for, desired grinding circuit performance. Subsequently, the pump and cyclone performances that provide the desired grinding circuit performance can be defined. Once the performance requirements of each process unit are determined, selection of physical equipment parameters that will deliver those performances can be carried out. The Functional Performance Equation shows that there are two distinct efficiencies in closed circuit ball milling. One of these, ?Circuit Classification System Efficiency? (CSE), is the fraction of ?coarse? material inside the ball mill upon which grinding energy is deliberately expended, versus the remaining fraction of ?fines? or finished size material inside the mill, upon which grinding energy is wasted (on over-grinding). The role of the pump and cyclones is to maximize CSE, which is the desired grinding circuit performance. The obtainable, target CSE for any given circuit can be estimated, for example by referring to a plant data base of CSE?s. Design/optimization guidelines then allow us to specify the pump and cyclone performances that will achieve the target CSE. This paper outlines the step-by-step, systematic method of pump and cyclone selection which maximizes CSE. Numerous examples of its successful application are provided.

Jan 1, 2011