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By P. de Vitry, Oliver Bowles

The conventional wire saw, introduced in the slate district of Pennsylvania by the Bureau of Mines in 1927, and used thereafter with remarkable success, consists of a three-strand steel cable having a diameter of 93/16 or 54 in. The equipment, methods used, and accomplishments have been described in previous reports.'-I Similar wire saws have been used extensively in Europe, in quarries and in shaping blocks and slabs. During the period 1932-1937, competition in European marble quarries was keen, prices were declining, and orders were not abundant. When orders were received, there was generally an urgent call for speedy delivery. Because of the diversification of demands, it was impossible to maintain in stock marbles of the color, size, and thickness called for, therefore the material generally had to be fabricated after the order was received. The wire saw enabled stone mills to fill such orders promptly. With skillful handling, 7/8-in. slabs could be cut accurately and rapidly with this equipment. It was found, however, that, as the three-strand wire became worn, the cutting speed dropped rapidly and the cut became less accurate. To overcome these difficulties the junior author of this paper, after much experimentation, developed a new type of wire consisting of a single ribbon-shaped strand, twisted as shown in Fig. I. To ensure straight sawing, the twist of the ribbon is reversed from right to left and vice versa every 25 ft. The reversal of the twist is shown in Fig. 2. This is not a new feature; it has been used to advantage with the three-strand wire both in Europe and America for several years. However, some difficulties arise in splicing the three-strand reverse-twist wire, and the claim is made that cutting is less accurate as the wire becomes worn. To make an endless belt, the ends of the single-strand wire are brazed together with Pyrophyllite is a hydrous aluminum silicate (A1²Si4O10(OH)²)1 that, occurs in both the foliated and the massive forms. The foliated variety resembles talc in that it has a greasy feel, a pearly luster, perfect basal cleavage, and usually is white, although in some deposits apple green, gray, brown, russet, and nearly black specimens may be found. The massive deposits of pyrophyllite yield pearl gray to light tan aggregates, some of which are so friable that they may be crushed with the hands into a fine gritty powder. Frequently specimens of the massive variety are studded with crystals of radial structure. The mineral has a specific gravity of about 2.7 and a hardness of 1 on Mohs' scale.' The chemical composition of commercial pyrophyllite reflects the mineralogy of the deposits, which, according to Stuckey12 contain pyrophyllite and quartz, together with chloritoid, sericite, and a few other minerals of negligible importance. The latter, he says, ('are noticed in but small quantities to the extent they might occur as accessory constituents of an igneous rock or as products of regional metamorphism or weathering. . . . Quartz is abundant everywhere except in the very best grades of pyrophyllite." Analyses of specimens from several deposits are listed in Table 1, showing that the silica content varies from 57 to 73 per cent and the alumina from 22 to 33 per cent. Oxides of iron and the alkaline metals are collectively present, with one exception, to an extent of about 1 to 1.5 per cent. Sources At present, North Carolina is the only commercial source of pyrophyllite, although the mineral has been found in small quantities in many parts of the world. The North Carolina deposits are in the "Carolina Slate Belt," which traverses the center of the state in a southwesterly direction. This belt varies from 8 to 50 miles in width. Two major deposits of pyrophyllite lie along its eastern boundary, in what is known as the Deep

Jan 1, 1942

By P. de Vitry, Oliver Bowles

The conventional wire saw, introduced in the slate district of Pennsylvania by the Bureau of Mines in 1927, and used thereafter with remarkable success, consists of a three-strand steel cable having a diameter of 93/16 or 54 in. The equipment, methods used, and accomplishments have been described in previous reports.'-I Similar wire saws have been used extensively in Europe, in quarries and in shaping blocks and slabs. During the period 1932-1937, competition in European marble quarries was keen, prices were declining, and orders were not abundant. When orders were received, there was generally an urgent call for speedy delivery. Because of the diversification of demands, it was impossible to maintain in stock marbles of the color, size, and thickness called for, therefore the material generally had to be fabricated after the order was received. The wire saw enabled stone mills to fill such orders promptly. With skillful handling, 7/8-in. slabs could be cut accurately and rapidly with this equipment. It was found, however, that, as the three-strand wire became worn, the cutting speed dropped rapidly and the cut became less accurate. To overcome these difficulties the junior author of this paper, after much experimentation, developed a new type of wire consisting of a single ribbon-shaped strand, twisted as shown in Fig. I. To ensure straight sawing, the twist of the ribbon is reversed from right to left and vice versa every 25 ft. The reversal of the twist is shown in Fig. 2. This is not a new feature; it has been used to advantage with the three-strand wire both in Europe and America for several years. However, some difficulties arise in splicing the three-strand reverse-twist wire, and the claim is made that cutting is less accurate as the wire becomes worn. To make an endless belt, the ends of the single-strand wire are brazed together with Pyrophyllite is a hydrous aluminum silicate (A1²Si4O10(OH)²)1 that, occurs in both the foliated and the massive forms. The foliated variety resembles talc in that it has a greasy feel, a pearly luster, perfect basal cleavage, and usually is white, although in some deposits apple green, gray, brown, russet, and nearly black specimens may be found. The massive deposits of pyrophyllite yield pearl gray to light tan aggregates, some of which are so friable that they may be crushed with the hands into a fine gritty powder. Frequently specimens of the massive variety are studded with crystals of radial structure. The mineral has a specific gravity of about 2.7 and a hardness of 1 on Mohs' scale.' The chemical composition of commercial pyrophyllite reflects the mineralogy of the deposits, which, according to Stuckey12 contain pyrophyllite and quartz, together with chloritoid, sericite, and a few other minerals of negligible importance. The latter, he says, ('are noticed in but small quantities to the extent they might occur as accessory constituents of an igneous rock or as products of regional metamorphism or weathering. . . . Quartz is abundant everywhere except in the very best grades of pyrophyllite." Analyses of specimens from several deposits are listed in Table 1, showing that the silica content varies from 57 to 73 per cent and the alumina from 22 to 33 per cent. Oxides of iron and the alkaline metals are collectively present, with one exception, to an extent of about 1 to 1.5 per cent. Sources At present, North Carolina is the only commercial source of pyrophyllite, although the mineral has been found in small quantities in many parts of the world. The North Carolina deposits are in the "Carolina Slate Belt," which traverses the center of the state in a southwesterly direction. This belt varies from 8 to 50 miles in width. Two major deposits of pyrophyllite lie along its eastern boundary, in what is known as the Deep

Jan 1, 1942

By Arthur La Motte

I NDUSTRIAL explosives, as distinguished from military explosives, include high explosives and blasting powder. The high explosives which are best known are straight dynamite, gelatin dynamite, ammonia dynamite and permissibles. There are two kinds of blasting powder, saltpetre blasting powder and nitrate of soda blasting powder. Blasting powders are mechanical mixtures of nitrate of potash or nitrate of soda with sulfur and charcoal, highly compressed, granulated and glazed. They ignite from a spark and burn with relative slowness, the rate of burning and hence the rate of conversion into gases depending upon the size of the granulation and upon the degree of. confinement under which the powder is placed. High explosives, on the other hand, are chemical compounds which detonate; that is, when the explosive is subjected to a violent shock, provided in practice by a blasting cap or an electric blasting cap, the molecule of the essential ingredient, usually nitroglycerin, is disrupted and the energy and heat released cause any other explosive ingredients which may be present, such as ammoniuin nitrate or T.N.T., to decompose with a resultant evolution of gases at an extremely rapid rate varying from 6000 to 20,000 ft. per second.

Jan 1, 1924

By Isabel F. Barton, J. Brent Hiskey

Chalcopyrite (CuFeS2) is the earth’s most abundant copper ore mineral, but is refractory to leaching with sulfates, chlorides, and other common lixiviants and oxidants. This has led to increasing research into alternative lixiviants for recovering Cu from chalcopyrite. Here, we review the leach kinetics of chalcopyrite in glycine, ionic liquids, and methanesulfonic acid, compared to baseline ferric sulfate and ferric chloride. Glycine (CH2NH2COOH) has long been used in applications such as biocatalysis and electroplating, and has recently been examined as a lixiviant for whole ores and concentrates of both copper and gold. It is nontoxic, biodegradable, and capable of strongly complexing Cu2+. Compatible oxidants are peroxide, dissolved oxygen, and ferric sulfate. Chalcopyrite leaching rate in glycine is chemical reaction-controlled, but the effects of grain size and the reaction orders with respect to lixiviant and oxidant concentrations and mass transfer vary. The use of ionic liquids as a leaching agent for chalcopyrite has been extensively investigated in recent years. This system is based primarily on the use of the imidazolium molecule (C3H5N2), which is a planar 5-member ring structure. This lixiviant has been applied to the leaching of chalcopyrite in the form of pure mineral, concentrates, and ores. Kinetics of ionic liquid leaching of chalcopyrite vary substantially depending on the type and concentration of ionic liquid. Methanesulfonic acid (HCH3SO3) is one of the newest lixiviants available in leaching, having only been examined in the last decade. It has been examined as a substitute for sulfuric acid, since it is less corrosive, is biodegradable, and breaks down to carbon dioxide and sulfate over time. The rate of copper leaching from chalcopyrite by methanesulfonic acid is controlled by diffusion and exhibits a strong dependence on oxidant type and concentration. Despite promising reaction rates and total extraction by some of these novel lixiviants, comparison with baseline ferric sulfate and ferric chloride systems makes it doubtful that any will be commercially viable in the near term. Only at very high reagent concentrations and temperatures, and/or very fine grain size, did any of the systems perform comparably to the much cheaper ferric chloride at extracting Cu from chalcopyrite. Most had similar overall reaction rates and total extraction to ferric sulfate, which is relatively common and cheap. However, the leaching kinetics of these novel lixiviants offer valuable insight into the dissolution behavior of chalcopyrite in various systems.

Jan 1, 2019

By Walter Valery, Sarma Kanchibotla

Due to the global financial crisis, the world economy has turned upside down and most major economies in the world are facing severe recession for the past one and half year. During this period most commodity prices have tumbled by more than half from their peaks and such a sudden and severe economic downturn is not seen since the great depression. This sudden drop in commodity prices and lack of credit made many mining operations unviable and even those mines that are marginally viable at this point are operating under severe cost pressures and capital expenditure restrictions.

Jan 1, 2010

By D. I. Hoyer

A preliminary model has been developed for autogenous pebble milling using information obtained from studies on ball milling and SAG milling. The model treats the breakage as the weighted sum of first-order breakage of smaller particles by tumbling pebbles, non-first order breakage of larger particles which are too large to be nipped properly by pebbles, autogenouS fracture and chipping of larger lumps to form pebbles, and autogenous fracture and abrasion of pebbles. The model includes the effects of residence time distribution, classification through the exit grate, and a mass transfer relation which describes the accumulation of fine material in the mill. Example simulations are given, based on breakage parameters determined from batch grinding tests in laboratory mills. fracture breakage and abrasion. In the development of these preliminary mass balance equations it will be assumed that breakage by fracture is first-order, but this assumption will be modified later in the paper. It will also be assumed that the residence time distribution of a long autogenous mill can be described by an equivalent series of m fully-mixed mills, with a classification action imposed on the mill contents by the discharge grate. Size distributions are expressed as a v2 geometric series, numbered 1 for the top size down to n for the fines, or "sink" interval. If the holdup in the mill is W then the rate of breakage of material in size interval i is given by SiwiW, where wi is the fraction of material in size interval i, and Si is -the overall specific breakage rate of size i material (fraction per unit time).

Jan 1, 1985

By T. Avilez, D. Salari

"The economics of developing gold deposits containing elevated levels of cyanide soluble base metals is often challenged by high cyanide consumption and increased operating costs. SART is a chemical process that enables cyanide consumed by base metals to be recovered and recycled for gold leaching. The process also provides concurrent recovery of the base metal to generate incremental revenue from the sale of high-grade base metal sulphide concentrates. Although SART was developed and successfully piloted by Lakefield Research and Teck Corporation in the late 90’s and is now a public domain technology, the adoption of SART has been relatively slow due to concerns about implementation costs and the reliability of metallurgical performance. Through extensive experience in selective metal sulphide precipitation applied to mining wastewater since 2007, BQE Water has provided process know-how, design along with operations and maintenance experience to a number of projects involving the integration of SART into various metallurgical flowsheets on an industrial scale. This paper presents the commissioning experience and operating data from a SART plant treating up to 500 m3/hr of leach solution at a heap leach operation in Mexico. INTRODUCTION One of the current trends in the gold industry globally is the increasing importance of complex polymetallic gold deposits as discoveries of large Carlin type gold deposits become increasingly rare (Sceresini, 2005). The presence of cyanide soluble copper and zinc in complex gold deposits necessitates changes to the traditional gold extraction metallurgical flowsheet. A tool available to the industry to help manage the interference of cyanide-soluble base metals in gold extraction is the SART (sulphidization-acidification-recycling-thickening) process. SART breaks the weak acid dissociable (WAD) base metal-cyanide complexes, precipitates the metals as high-grade sulphide concentrates and makes the freed cyanide available for recycle."

Jan 1, 2018

By John F. Gamble

Amphiboles are hydrated mineral silicates five of which occur in asbestiform habits as asbestos grunerite (amosite) asbestos, riebeckite (crocidolite) asbestos, anthophyllite asbestos, tremolite asbestos and actinolite asbestos] and non-asbestiform habits (grunerite, riebeckite, anthophyllite, tremolite and actinolite). The asbestiform varieties are characterized by long, thin fibers while non-asbestiform varieties such as cleavage fragments form short fibers with larger widths. The U.S. regulatory method for counting asbestos fibers (aspect ratio [>]3:1, length [>]5 µm) does not distinguish between asbestos and cleavage fragments. The method biases toward increased counts of non-asbestiform cleavage fragments compared to long, thin asbestos fibers. One consequence of this regulatory approach is that workers can be erroneously classified as exposed to concentrations of asbestos (asbestiform amphiboles) above the U.S. 0.1 f/mL exposure standard when in fact they are not exposed to asbestos at all but non-asbestiform amphibole cleavage fragments. Another consequence is that the known carcinogenic effects of asbestos may be falsely attributed to non-asbestiform amphibole cleavage fragments of the same mineral. The purpose of this review is to assess whether amphibole cleavage fragments pose the same risk of lung cancer and mesothelioma characteristic of amphibole asbestos fibers. We identified three groups of workers exposed to non-asbestiform amphiboles: two groups exposed to grunerite (Homestake gold miners and taconite miners) and one group exposed to industrial talc containing non-asbestiform tremolite and anthophyllite in St. Lawrence County, NY. In addition to assessing strength of association and exposure?response trends in the non-asbestiform amphibole cohorts, comparisons were also made with cohorts exposed to the asbestiform counterpart (positive control) and cohorts exposed to the mineral (e.g. talc) that does not contain amphiboles (negative controls). The cohorts exposed to non-asbestiform amphiboles had no excesses of lung cancer or mesothelioma. Similar results were observed in the negative control groups, in stark contrast to the excess risks of asbestos-related disease found in the asbestos cohorts. The only possible exception is the twofold increased risk of lung cancer where exposure was to industrial talc containing cleavage fragments of tremolite and anthophyllite. However, this risk is not considered attributable to the talc or amphibole cleavage fragments for several reasons. A similar increased risk of lung cancer was found in Vermont talc workers, studied in the same time period. Their exposure was to relatively pure talc. There was no relationship between lung cancer mortality and exposure measured as mg/m3 years and years worked. A case?control study reported that all the lung cancer cases were smokers (or former smokers) and attributed the excess to smoking. There were two mesothelioma cases among the NY State talc workers exposed to cleavage fragments of tremolite and anthophyllite, but talc is not a plausible cause because of too short latency and potential for previous asbestos exposure. The positive controls of tremolite asbestos and anthophyllite asbestos exposed workers showed excess risks of both lung cancer and mesothelioma and positive exposure? response trends. St. Lawrence, NY talc does not produce mesotheliomas in animals while amphibole asbestos does. In sum, the weight of evidence fully supports a conclusion that non-asbestiform amphiboles do not increase the risk of lung cancer or mesothelioma. ©2008 Published by Elsevier Inc. Keywords: Amphiboles; Cleavage fragments; Lung cancer; Mesothelioma; Asbestos; Non-asbestiform amphiboles; Grunerite; Talc

Jan 1, 2007

By A Hanna

Quarries around Auckland have reached or are reaching the ends of their lives, which raises issues about rehabilitation. Significant volumes of 'cleanfill' are generated by the City, particularly during phases of urban renewal and development. Emplacement of the fill in quarries removes the problem of fill disposal and provides an opportunity for restoration of the quarry site.There is a compatibility between quarrying and cleanfilling because at quarries:Truck routes are already established Neighbours are accustomed to the effects and appropriate buffer distances have been established Bringing fill into a site attracts aggregate sales and is very efficient. Fill originates from construction sites and ad-hoc excavations and therefore it is not surprising that sampling has shown the quality to be variable. Both Winstone and the Auckland Regional Council have surveyed undisturbed soils in the region to attempt to determine natural background levels of common contaminant substances. Comparison of these levels with delivered fill shows that a high proportion of delivered materials can be regarded as mildly contaminated. Therefore the term 'cleanfill' is, in the Auckland region at least, a misnomer and the term 'managed fill' has been adopted.Historically and presently the only control on quality of 'cleanfill' has been some visual inspection. This leaves the fill operator open to potential liability for creating a contaminated site. Implementation of controls at WinstoneÆs operations has progressed slowly, over some ten years. This is mainly due to the perception that mobility of contaminants within and out of the landfill will be very limited because of the near-neutral pH and abundance of clay minerals in the fill. The methods of control and results of environmental risk assessments at WinstoneÆs Puketutu Island Quarry will be briefly described.

Jan 1, 2002

By R. H. Hanewald

The INMETCO process has been modified so as to recover nickel. chromium and Iron from a wide variety of metal containing waste-streams. This now includes the recovery of metals from spent acid solutions such as chromic acid etching I1quids. nJcke1 and chromium plating solutions; stainless and superalloy pickling solutions. etc. In addition. hazardous electric furnace stainless steel and. superalloy baghouse bags can be processed so as to recover the valuable metall1cs. A detailed review of the above new recovery techniques w1ll be discussed as well as the current operating methods used at INMETCO.

Jan 1, 1992

By Yoshihiro Kawarabata

INTRODUCTION With only about 30% of Japan's entire population served by sewer systems at the end of 1980, extensive sewerage construction programs have been implemented. As major sewer networks in large cities are near completion, construction of smaller sewer networks in less populated areas and branch sewers in urban areas is on the rise, where a demand for sewer tunnels of 600mm to 1500mm diameter is very heavy. The pipe jacking technique, usually employed to excavate such small diameter tunnels, therefore has become the subject of further technological development and sophistication to cope with the increasing volume of construction. At the 1979 RETC, the state of the art on the slurry shield tunneling method at that time was reported. This paper is a follow up to the last paper and discusses a newly developed boulder crushing equipment and automatic pipe jacking system for the slurry shield method and their application. Such technological advancement as high-degree mechanization and automation will significantly improve tunneling operations in response to the aging society to come. Through application of the technique on so called factory automation, this is a step towards field automation for the construction industry.

Jan 1, 1983

By F. M. L. Mulaudzi

Metal dusting is a corrosion phenomenon that occurs in strongly carburizing gas atmospheres at elevated temperatures. Reaction kinetics and product characterizations of Alloys 602CA and 800 were examined by scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX) and X-ray diffraction (XRD).The results showed that Alloy 602CA is more resistant to metal dusting than Alloy 800. Visual examination and SEM surface analysis showed that Alloy 800 suffered metal dusting attack after a relatively short exposure period. The amount of coke deposits increased on Alloy 800 with increased exposure from 96 to 336 hours. X-ray diffraction on the reacted surfaces identified graphite and austenite in both alloys and some iron oxides/spinel for Alloy 800.

Jan 1, 2012

By G J JAMESON

The flotation cell has undergone a number of changes since the process was first introduced in Broken Hill in the early years of this century. The development of the mechanical flotation cell is reviewed, followed by a discussion of more recent developments such as the flotation column, the air-sparged hydrocyclone, the Wemco-Leeds cell, the Bahr and Deister columns and the Jameson cell.

Jan 1, 1992

By W. X. Wang, O. Stephansson

In the mining and quarry industries, rock fragments are often transported by conveyor belt. To estimate the qualities of the rock fragments (i.e., size distribution and shape), an operator must take samples from the conveyor and manually perform a sieve analysis, which is time-consuming and tedious. Alternatively, an image-analysis system can be used to monitor the fragment quality on a fast moving conveyor belt. However, images of fragments on a fast moving belt vary to such a degree that the quality of any two successive images are not the same, and some of the images are of such poor quality that they are unrecognizable by human eyes. If poor-quality images are directly analyzed by a segmentation algorithm, the analysis will not be satisfactory. To resolve this problem, it is necessary to use an image-classification program for the automatic selection of fragment images with good quality. Because of this need, an image-classification program was developed and tested both in the laboratory and in the field Testing of the system on different types of fragments showed that the system works reasonably well.

Jan 1, 1997

By W. H. MacLean, S. Liaghat

Abstract- The Key Tuffite is a thick (0.3 m to 6 m) and laterally extensive (-10 km) cherty, sulfide-bearing tuff unit in Archean greenstones in the Matagami mining district in northwestern Quebec. It lies at the contact of the Watson Lake Group and overlying Wabassee Group volcanic rocks, and is host to major Zn-Cu volcanogenic massive sulfide deposits. The tuff component is highly altered and its volcanic precursors are not identifiable by petrographie means. The tuff is mixed with a volcanic exhalative component comprising chert, carbonate and sulfides (pyrite, pyrrhotite, and minor sphalerite and chalcopyrite). The normative mineral composition of the Key Tuffite is 33% quartz, 28% sulfides, 16% sericite, 8% carbonate, 60Jo chlorite and 9% other minerals. In the vicinity of the Bell Allard and Orchan mines, the precursor tuff components are identified using immobile major and trace elements, as Watson Lake tholeiitic rhyolite (Zr/Y = 1.5 to 3.5, LaN/Ybn. = 1.7 to 2.8, Si02 = 72.5 ± 1.2 wt %, and Wabassee calc-alkaline andesite (Zr/Y =9, LaN/Ybn. = 4 to 8, Si02 = 56% to 65%). Immobile element computation techniques were used to calculate mass additions and losses in the conversion of the tuff to the Key Tuffite. Average net amounts of Fep3 (27% total iron), Si02 (14%), CaO (8%), S and K20 ( + 2%), were added, Na2O was removed (-2.8%), and MgO was over-all unchanged. Total net mass change was +63%, which comprises mainly exhalative additions, but also includes changes owing to hydrothermal alteration of the tuff component.

Jan 1, 1992

By Michael McVay

The use of augered cast-in-place piles has seen tremendous growth under commerical structures in the past twenty years. Problems with vibration, soil densification and/or heave associated with driven piles do not occur with properly installed augered piles. Augered cast-in-place piles were originally constructed (1950s) with diameters of .31 m (12 in.) and lengths up to 6.1 m (20 ft); however with the advent of better drilling equipment, diameters varying from .41m(16 in.)to .61 m (24 in.) and typical depths ranging from 18.3 m (60 ft) to 24.4 m (80 ft) are achievable. Reinforcement may vary from a single high strength rebar (Grade 60) at the top of the pile to a continuous steel cage depending on loading (compression, tension-uplift, and lateral). Typical axial design loads (compression) for a single augered cast-in-place pile are in the 445 kN (50 tons) to 890 kN (100 tons) range.

Jan 1, 1997

Major activities of the Bureau of Mines Explosives Research Center during fiscal year 1965 (July 1, 1964, to June 30, 1965) are reviewed briefly. Part 1 summarizes significant accomplishments of the projects that were active during the report period. Part 2 presents short abstracts of the publications that appeared in the Bureau series and in other media during fiscal year 1965. Publications issued after June 30, 1965 are noted where pertinent in footnotes but are not abstracted.

Jan 1, 1966

By L Avalos, F Melo Miranda, J Misle, M Ingwersen

"Los Pelambres, majority owned by the Chilean company Antofagasta Minerals, is one of the leading producers of copper and molybdenum in the country. It is located high in Andes Mountains, over 3000 metres above sea level, 316 km from the nation's capital, Santiago.The maintenance service supplied to Los Pelambres over the past 13 years has evolved to the point that FLSmidth now provides an integrated service crucial to the management of their customer's assets. The contract initially involved specialty mechanical, electrical and instrumentation maintenance and has developed to encompass maintenance planning and plant control systems.The integrated partnership has delivered excellent results in the areas of improved availability, reliability and return on investment. The operation is now amongst the industry leaders in plant availability.The integrated maintenance service has delivered: An increase in plant availability from 93%, in the first year, to 96.5% today, generating approximately $50 million additional income per year, Quality work procedures, Process and equipment improvements, Major shutdown planning involving more than 700 personnel, 6000 parts and over 2 000 discrete activities.The ongoing success of the partnership requires a high level of understanding between both companies. A commitment to maintain a long term sustainable relationship, based on a ""win - win"" culture, is the key to this success. In this regard Los Pelambres has been a pioneer in establishing and developing such relationships.This case study will share the lessons learnt, the measures taken to improve performance and the best practices adopted during the 13 year evolution of the maintenance service partnership.CITATION:Misle, J, Melo Miranda, F, Avalos, L and Ingwersen, M, 2013. Integrated maintenance services at the Los Pelambres Mine in Chile - The lessons learnt and best practices developed from a long-term sustainable relationship, in Proceedings MetPlant 2013 , pp 296-331 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jul 15, 2013

By D. W. Frommer, M. M. Fine

"INTRODUCTION Laboratory mineral-dressing investigations covered by this report show that ores from Montgomery County, Ark., and Morgan County, Mo., are potential sources of barite and zinc. Fine grinding and froth flotation yielded drilling-grade barite from the former and chemical-grade barite and zinc concentrates from the latter.Samples from these deposits were subjected to a laboratory investigation to develop an economic and feasible treatment. The Arkansas ore, submitted by the Husky Refining Co., consisted of an intimate mixture of the economic mineral and quartz. Fine grinding and fatty acid flotation were utilized to effect a good recovery of a drilling-grade product. The other was a zinc-barite ore submitted by the Rocky Ford Mining Co., Stover, Mo. There was no problem in the recovery of zinc (most of which occurred as sphalerite), but the recovery of barite by flotation was complicated by the presence of gangue carbonates. Ultimately, an excellent recovery of barite was achieved with a relatively new type of flotation promoter, petroleum sulfonate.In recent years, barite has become one of the major industrial minerals as an essential ingredient in heavy drilling fluids, pigments, and chemicals. New sources of this important commodity are always interesting; thus, it is the purpose of this report to present information that may permit commercial exploitation of two deposits not in production."

May 1, 1952

By H. H. Campbell

MANY attempts have been made to write a formula by which to calculate the strength of steel from its chemical composition, but most of these endeavors have failed because there were too many disturbing conditions. It is idle to collect from the pages of trade-papers, books, or the proceedings of scientific societies, a multitude of observations. The combination of such results will simply show that steel of the same composition will vary in tensile strength through wide limits-a fact that has been known for generations. That cold-working, overheating, and many another form of heat-treatment alter fundamentally the strength of steel, is ancient history, although it is only recently that the microscope has pointed out the road to an explanation of the phenomena. It may be urged that the microscopic structure must be taken into consideration in any formula giving the ultimate strength, but from the standpoint of the present investigation this is unnecessary. We are trying to determine primarily, not what changes in ultimate strength may be made by variations in the condition of carbon, but what effect is produced by changes in the amount of carbon, when its condition remains constant. For such an inquiry, in order that the condition of the carbon should remain as nearly uniform as possible, it is essential that all test-pieces be made under the same conditions; and it is be¬lieved that the tests described in this paper satisfy that require¬ment. The investigations were made at the works of the Pennsylvania Steel Company,. Steelton, Pa.; the ingots from which the tests were made were 6 in. square in every case; they were heated in the same furnace and forged at the same ham

Jan 1, 1905