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By K. M. Kim

A site-specific blasting model has been developed for the Asarco Mission mine. The main inputs to the model are the in-situ block size (F80), the post-blast fragmentation (P80) and the intact tensile strength (To). The output from the model is the specific blast energy (ESE). Modern techniques are being used to obtain the input parameters for the site-specific blast fragmentation model. In particular, image processing software is used to obtain both the in-situ block size and the post-blast fragmentation, and the Schmidt hammer is used to obtain the tensile strength at numerous locations throughout the rock mass. An initial model was developed using five test shots in one area of the mine that contains Argillite and is relatively homogeneous. This also included calibrating Schmidt hammer readings against actual Brazilian tensile measurements. The model for Argillite will be updated as more tests are conducted, and the model will be extended to the other four primary rock types at the Asarco Mission mine.

Jan 1, 2011

By Jack E. Brockway

As tunnel boring machine technology has expanded, so has its range of application. Tunneling machines (TBM's) are tackling tasks today that fifteen years ago were considered "inappropriate". A case in point is incline/decline TBM boring. An incline or decline bore presents peculiar design considerations that differentiate it from a horizontal bore. This paper reviews those design considerations as they apply to TBM's, backup, muck handling and other tunneling subsystems. In addition, several abbreviated case studies are presented. By the review of real life tunneling techniques as well as design considerations, the "appropriateness" of TBM incline/ decline boring today becomes apparent. INCLINE Introduction In contemplating the impact of incline versus horizontal tunnel boring system design, the obvious consideration is gravity. Up-hill boring can be quite different than horizontal boring. Muck, water and machine weight all tend to slide down the incline. In addition, hydraulic and lubrication systems if unaltered, will find their fluids pooled in the lower corners contentedly ignoring such higher elevation items as gears and bearings. In order to address this inherent gravity problem, a review of

Jan 1, 1983

By N. Abdel-Khalek, A. Youssef

The tailings from beneficiation of Florida phosphate ore contain considerable phosphate values. These tailings are currently discharged into large disposal areas. More than three million tons of P2O5 are discarded with the phosphatic slimes (clays) in Florida each year. These phosphatic clays not only create one of the most difficult disposal problems in the mining industry, but also represent a tremendous loss of P2O5. As the quality and quantity of Florida’s phosphate reserves diminish, recovery of phosphate values from these wastes becomes more vital. This will also significantly lengthen the life of these important phosphate resources. Thus, it is the goal of this study is to recover more than 80% of the phosphate values in phosphatic clays. A systematic study to characterize samples taken from inactive disposal area has been conducted. The data suggest that natural segregation takes place in the settling pond. In other words, coarser particles settle closer to the feeding point of the pond. Flotation tests were conducted using the +325 mesh fraction of samples obtained from sites close to the feeding point (sample# A) and further from that point (sample# B) and (sample# C) which is even further away from the feeding point. The results show the following: Sample# A gives the highest grade and recovery, followed by that of # B and then of # C. There is a great potential to upgrade sample# A where concentrates of high grade (68.9-70.1 % BPL or 31.5- 32.1% P2O5) and recovery (~86.6-95.4 %) can be obtained under the investigated operating conditions (1.0 – 2.0 kg/ton sodium silicate and 1.5—3.0 kg/ton collector mixture of fatty acid and fuel oil). The mineralogical and chemical analysis of all samples is presented in this paper for comparison. Only in this paper, the flotation data of (site # A) are discussed below.

Jan 1, 2002

By N. E. Lehman

Cordilleran metamorphic core complexes in the southwestern United States are areas where middle to late Tertiary low-angle normal faulting has uncovered rocks that were at temperatures sufficient for mylonitization during the early part of Tertiary extensional faulting. Large-displacement low-angle normal faults that separate upper-and lower-plate rocks in metamorphic core complexes are termed detachment faults. The significance of Tertiary detachment faulting in the Basin and Range Province has only become apparent in the past 6-8 years, and the association of mineral deposits with detachment faults has only been recognized in the past few years as well. Crystalline rocks below detachment faults have typically undergone chloritic alteration and brecciation over a distance of a few to a few hundred meters below the fault surface (Fig. 1). Chloritic alteration and brecciation overprinted mylonitic fabrics formed during earlier ductile shearing along the down-dip projection of detachment faults. Rocks that underwent pre-Tertiary ductile deformation and prograde metamorphism were subjected, in rapid succession, to middle to late Tertiary mylonitization, brecciation and chloritic alteration, microbrecciation immediately adjacent to the fault, and subaerial exposure. Lower-plate rocks thus experienced rapid decompression and cooling as a result of tectonic denudation and isostatic uplift (Wernicke, 1981; Davis, 1983; Davis et al., 1986).

Jan 1, 1987

By Paul Sarnoff

The economics of precious metals -- depending upon who is involved --could be the economics of hope, of fear, indeed of profit and perhaps survival. For those investors seeking capital gains in a puzzling economy, precious metals involve the economics of hope. Those who are convinced that currency soon won't be worth the paper it's printed on turn to precious metals because of the economics of fear. Gold and silver have been a storehouse of wealth since biblical times. The economics of fear during the past 500 years on the Continent has caused almost every European family to make sure a private stockpile or hoard of gold, silver or coins is at hand in case the paper currency of their country undergoes the kind of disaster that came to the German Mark after World War I. Understandably, for mining companies involved in the production of precious metals, the elements of operations and management are directly concerned with the economics of profit -- and perhaps survival. To the American miner the price of precious metals in the marketplace is a matter of daily concern. After decades of selling silver to the US Government at 64.64 cents an ounce, producing silver mines suddenly became faced with prices breaking $5, $10 and $20 per ounce, and approaching $50 an ounce during the period 1978-1981. What should the miner expect one year in the future? Five years?

Jan 1, 1981

By A. F. Marques

The Azores islands are located on a triple junction where the American, African (AFR), and Euroasian (EUR) plates meet. The Mid-Atlantic Ridge (MAR), oriented N-S, represents two branches of the T; an E-W branch defines the EUR/AFR boundary called the Terceira Rift. The nature and structure of this plate boundary, as well as the dynamics of the interaction of tectonics and volcanism remain unconstrained. The Azores plateau is seated on a mantle domain of anomalously low seismic S-wave velocities, and gravity and geoid anomalies, where the apparent thick crust is thought to relate to larger degrees of melting initiated at greater depths [1]. The cause of these anomalies is controversial but many authors consider the presence of an anomalously hot/wet enriched mantle probably supplied by a plume [2]. The geochemistry of the subaerial and most submarine lavas from the plateau reinforces the plume model beneath the Azores [3-4]. The origin, size and present location of the plume is under debate but an area near Terceira is the favoured plume centre [5]. [ ] SEAFLOOR HYDROTHERMAL SYSTEMS IN THE AZORES AREA (36ºN ? 40ºN) More than 150 active and fossil hydrothermal systems are known in the oceanic seafloor [6]. Many more are yet to be found on vast oceanic areas that haven?t been explored [7]. Ever increasing knowledge shows that modern seafloor hydrothermal systems can be hosted in felsic to ultramafic rocks, vary in size and shape and exhibit diverse amounts of sediment cover

Jan 1, 2011

By RIINA SALMIMIES, Paula Vehmaanperä, Antti Häkkinen

The dissolution of iron oxides in mixtures of acids is fairly uncommon but can result in a more efficient dissolution process. The objective in this work was to investigate the dissolution of synthetic hematite powder in mixtures of oxalic and sulfuric acid. Experiments were done at different acid ratios and temperatures. An increase in temperature from 15 to 35 °C increased solubility, whereas an increase from 35 to 50 °C did not change the solubility but had a profound effect on the kinetics. An important finding was that oxalic acid advanced the dissolution process since increasing the amount of oxalic acid in the system resulted in faster kinetics and higher solubilities. The dissolution kinetics were well described with the Kabai model, which was the only studied model able to describe the whole reaction time. However, the solid specific constant a varied for the different acid ratios and this is argued to be a result of changes in the solid phase. The changes in the constant a were not in line with the original study of Kabai, which indicates that a cannot be the solid specific constant but it can be the constant connected to dissolving media describing the changes in the dissolution mechanism.

Sep 23, 2020

By Larry S. Diaz

The paper considers the selection of control instrumentation for a modern flotation plant, as well as the best interpretation and most effective use of the process data obtained. Process control computer availability is considered from the outset. A general philosophy of control is proposed which leads toward a system that is its own reliability monitor. The bulk of the problems are in grinding and classification. Alternative control methods are described that use particle size measuring devices. Flotation controls, based to a large extent upon on-stream X-ray analysis, are reviewed in detail. Reagent control methods are also examined. Methods to analyze the data obtained from the various measurement devices are introduced. These methods would enable an estimate of the validity of the data and require some redundant information. Another objective of these methods is the protection of operating equipment from possible control malfunctions. Although the discussion generally considers some degree of computer usage, this paper attempts to describe instrumentation and data analysis methods that enable control with or without the process control computer.

Jan 1, 1972

By S. James Campbell

Ladies and Gentlemen: Never in the history of our mining industry has the emphasis on public relations been accelerated as much as it has in the last few years. Knowing of your keen interest in this subject I consider it a great privilege that your program committee has asked me here to discuss the crushed stone segment of our industry approach to this important part of our daily business lives. As you are aware, crushed stone operations are present in almost every segment of the country wherever aggregates for construction projects are required. The tonnage of crushed stone produced is second only to sand and gravel - another source of aggregates - and this together with sand and gravel amounts to over half of the tonnage of all mined products in the United States. What is unique about this industry that will be of interest to all of you in analyzing how they have approached Public Relations? The fact that it is so wide-spread is of course obvious, but perhaps a more significant nature of this segment of the mining industry that has brought it more in the limelight of public interest and on a larger scale is the location of a large part of the quarries quite close into the urban area and population centers where you have the greatest demand for aggregate products.

Jan 1, 1969

By Ihor A. Kunasz

Lithium minerals occur predominantly in pegmatites that contain mineral assemblages derived from the crystallization of post- magmatic fluids or from the metasomatic action of residual peg- matitic fluids. They have been the traditional sources of raw material for ceramic and chemical industries. With the discovery of the Searles Lake deposits, brines became new sources of lithium, and, today, two brine deposits satisfy nearly one-half of the free world demand for lithium chemicals. Indeed, lithium production from pegmatites has been superseded by brines sources. In the United States, the brines of Clayton Valley, NV, have been exploited since 1964 by Cyprus Foote Mineral Company, a subsidiary of Cyprus Minerals Company. In Chile, Sociedad Chilena de Litio Ltda., an affiliate of Cyprus Minerals Company, is now producing lithium carbonate from the brines of the Salar de Atacama. Recently identified brine deposits suggest that these may well become the prime sources of lithium chemicals. In Bolivia, the government is negotiating the rights to exploit the brines of the Salar de Uyuni. The Salar del Hombre Muerto in Argentina is being evaluated as a future center of chemical production. The brines of the Great Salt Lake of Utah, the Smackover Formation, and the Imperial Valley geothermal field have been defined as important resources of lithium. In Tibet, high concentrations of lithium have been reported in several saline lakes. In the People's Republic of China, lithium may be produced from the brines of the Dabusan playa in the Qinghai Basin. The 1950s saw a great number of lithium companies develop. However, following the termination of the Atomic Energy Commission purchase program in 1959, several companies, such as Maywood Chemical Co., American Lithium Chemicals, and Quebec Lithium Corp., were forced to close their operations. Nevertheless, with the development of new applications in glass ceramics, air conditioning systems, synthetic rubber, and metallurgy (aluminumpotlines), the lithium industry grew steadily. With the potential application of lithium metal in batteries, nuclear reactors, and fuel cells, a steady growth can be foreseen. New products and new applications are likely to stimulate exploration for expanded reserves as well as the search for new sources from which lithium could be extracted economically. Presently identified reserves and production capacity are sufficient to satisfy the conventional market growth of lithium.

Jan 1, 1994

By CHRISTOPHER D. HEBERT, SCOTT W. HOFFMAN

All Rights Reserved. Printed in the United States of America. Information contained in this work has been obtained by SME, Inc. from sources believed to be reliable. However, neither SME nor its authors guarantee the accuracy or completeness of any information published herein, and neither SME nor its authors shall be responsible for any errors, omissions, or damages arising out of use of this information. This work is published with the understanding that SME and its authors are supplying information but are not attempting to render engineering or other professional services. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. Any statement or views presented here are those of individual authors and are not necessarily those of the SME. The mention of trade names for commercial products does not imply the approval or endorsement of SME.

Dec 1, 2019

By E. R. Bauer

In response to the mandates in the MINER Act of 2006, NIOSH conducted refuge alternatives research that included characterizing the utility, practicality and survivability of refuge chambers and outby safe havens. NIOSH also prepared and delivered a report to Congress in late December 2007 that summarized the findings of the research, included recommendations concerning the design and performance specifications for refuge alternatives, and focused on specific information that could inform the regulatory process on refuge alternatives. This document highlights NIOSH's research and recommendations concerning refuge alternatives, survivability evaluations of refuge chambers, and presents a brief review of the current deployment of refuge chambers in underground coal mines in the U.S. The research has lead to the conclusion that refuge alternatives have the potential for saving the lives of mine workers if they are part of a comprehensive escape and rescue plan, and if appropriate training is provided. DISCLAIMER: ?The findings and conclusions in this report have not been formally disseminated by the National Institute for Occupational Safety and Health and should not be construed to represent any agency determination or policy.?

Jan 1, 2009

By LUIS ALBERTO TORRES-CRUZ

The assessment of liquefaction vulnerability is crucial to understanding the potential consequences of a tailings dam failure. The “Plewes method” is a relatively well-known and simple screening method to assess liquefaction potential based on results of cone penetration testing (CPT) which may be complemented with laboratory testing. The objective of the current work is to emphasise the screening nature of the method and its uncertainties when applied in tailings deposits. Specifically, the paper highlights the difficulties in assessing the intrinsic uncertainty of the method and the additional uncertainty that results from variations of the slope of the critical state line (λ10) along the depth of the CPT sounding. The results of the method are too uncertain for detailed characterisation of tailings even when a relatively low intrinsic uncertainty is assumed. However, the method characterises weaker soils with lower uncertainty (although still too high for detailed characterisation) than stronger soils. The uncertainty of the method is negatively affected by the relatively low λ10 values that are typical of nonplastic tailings. It is suggested that the results of the method should be presented in scatter plots in which the spread of the data is consistent with the uncertainty of the method.

Jan 28, 2021

By William L. Young

There is an old saying in Canada: "Mines are made as much as discovered." What follows is Young's perception of his experience developing and financing the Cochrane Hill gold mine project. In 1974, I came back from rutile and zircon exploration and mining in Australia. I became interested in a copper, lead, and zinc project in the Bathurst District, New Brunswick. Much field work had already been done but I was convinced that a reinterpretation of the geophysical work left room to enlarge on the known mineralization. So, with my own money I put a property deal together, found an underwriter willing to raise $100,000, and had a lawyer produce a prospectus. The prospectus was ultimately accepted for filing by the Ontario Securities Commission and I acquired funding and began work. It did not take many drill holes to determine that the interpretation was not geologically valid. However, while drilling was going on, geophysical and geochemical explorations indicated interesting anomalous zones elsewhere on the property. But by now the base metal market climate had soured and the $50,000 I had left was not enough to evaluate the new results. So I decided to farm out the property. A data folio was produced and the property was optioned to a major mining company, with Northumberland Mines Ltd. retaining a 20% free, carried interest. By 1976, the market for junior issues was so bad no under¬writer would even talk to a geologist and I still had the $50,000 in the bank and was looking for something to initiate. A Project That Went Nowhere Market research indicated that the Toronto area imported fine calcium carbonate fillers from Georgia, Alabama, and Vermont. I was aware of the specs and the fact that there is a large marble belt in Eastern Ontario. After some prospecting, I found an interesting deposit. The product was slightly high in silica and low on brightness. Research work eliminated the silica and corrected the brightness. So, with insufficient money we launched a feasibility study. This included diamond drilling, bulk sampling, special fine grinding and air classification tests, and an in-depth market survey. Our product was as good or better than those on the market. Our advantage was that delivery could be made by a two-hour truck haul to the customer. The present system of rail delivery had many problems, especially in winter. Despite everything looking rosy, we ran into a stone wall. The underwriters were singularly unimpressed because the public saw little glamour in a substance most people had never heard of. The issue would have been difficult-if not impossible-to sell. Banks and government agencies took the position that if we could get long term take-or-pay contracts then they would lend the required capital. None of the suppliers, however, would even consider a contract until production had begun and they could evaluate the production material. It was a classic "catch 22" situation. I have gone into this in some detail to show how tough the industrial mineral market can be. We eventually optioned this calcium carbonate property to a major corporation. The option agreement would give us a free, carried 15% and the right to buy up to 40% for contributing 25% of the production costs. But the experience left my company in poor financial shape. To survive, I think the entrepreneur-geologist must always have at least one project in reserve, an emergency plan. I had been searching out a new project to work on, after the calcium carbonate option was wrapped up. It was gold. Gold intrigued me and I knew quite a bit about Nova Scotian gold. I felt that with any rise in price, many of the former high-grade gold mines would have interesting potential for the larger, low grade portions of the deposits. That is how I happened on Cochrane Hill, where much work had been done in the early 1970s when gold as $4.82/g ($150/ oz). This time my timing was good. No sooner had Northumberland signed an option agreement than gold prices started to rise. In six months, they went to $27.331g ($850/oz). Even so, financing gold prospects in early 1980 was still not easy. It had been years since gold financing had been undertaken. A whole new generation of investors, with no knowledge of gold mining, had grown up. So, with accounting and legal council, we decided on a semiprivate "seed money" offering. Under the new Ontario Securities Act, this was a new-and partly tax sheltered-concept. At the time, it was very innovative.

Jan 6, 1982

By Michael A. Piepenburg

The East Side Access (ESA) Project will extend Long Island Rail Road (LIRR) into midtown Manhattan via 11 km of tunnels, a new terminal station and associated support facilities. In addition to the hard-rock tunneling currently underway in Manhattan, soft-ground tunnels in Queens will traverse beneath Amtrak?s Sunnyside Yard and Harold Interlocking, the busiest rail interlocking in North America. This paper details ESA?s coordinated approach to interfacing with both Amtrak and LIRR with regard to the planned tunnels, shafts and related construction beneath or adjacent to the operating railroads. This interface includes integration of railroad staff, extensive presentations, reviews and agreements with the railroads regarding settlement mitigation, real-time automated geo-instrumentation monitoring, ground improvement, and geotechnical/environmental controls.

By J. Yianatos

The collection zone residence time distribution (RTD) of mechanical self-aerated flotation cells was characterized for liquid and solid per size class (-45 mm, +45-150 mm and +150 mm). It was found that a single large industrial cell with a volume of 130 to 250 m3, now used in plant operations, can be well represented by an LTST (large and small tank-in-series) model plus dead time. From a scale-up point of view, results showed a similar mixing behavior for industrial cells ranging from 130 to 250 m3. Also, single mechanical cells showed a similar mixing pattern (RTD) when compared to large pneumatic flotation columns. It was confirmed that for practical purposes, the mixing condition in a flotation bank of three or more cells in series can be well described by the classical N tanks-in-series model.

Jan 1, 2008

By Mark Lawshe, Shosie Serata

The conventional method of mining underground, using narrow rooms and wide pillars, has proven to be poorly adapted to the powerful earth forces that act on underground openings. The high costs of roof bolting, timbering, steel arching, and other means of artificial roof support for both room-and--pillar operations and longwall gate roadways attest to the limitations of traditional mine design. Too often, productivity halts when corners buckle under "cutter roof' stresses, floors heave, and roof strata fall. In the 1960s, an entirely different approach to strata control was developed. The Stress Control Method (SCM) stabilizes failing roofs and heaving floors by removing the cause of failure - highly concentrated stresses around the openings. This is achieved by regrouping three to 10 rooms into a single entry where the rooms are separated by very narrow yielding but stable pillars. SCM employs a specified excavation sequence to redirect earth pressures away from the mine openings. The yield pillars act as scaffolding until a permanently protective secondary stress envelope forms around the entry (lower part of Fig. 1). The result is a dramatic improvement in roof stability and a significant reduction in artificial support costs. Some roof bolting must still be done, mainly to meet Mine Safety and Health Administration (MSHA) requirements. Potash, salt, coal mining The stress control method was first applied to the deep potash mines of Saskatchewan. The new SCM design actually increased room widths to enlarge the stress envelope, redistributing the stress concentration away from the entries (Serata and Schultz, 1972). This resulted in a turnaround from pervasive roof fall/floor heave conditions that threatened operations in the eight new mines opened in the Saskatchewan potash field during the 1960s. In addition to eliminating all roof bolting, SCM successfully stabilized ground conditions and substantially increased productivity over the original design (Serata, 1976, 1982). Similarly, the deep Boulby potash mine of Yorkshire, England, was about to close after various conventional means of combating roof failure had failed. An SCM test area was excavated that resulted in the ground quickly stabilizing without need o artificial support (Serata, 1982; Chilton and Laird, 1982). Another example is the Diamond Crystal salt mine in Louisiana. Here, multiple level mining was being extended from the third to the fourth level downward in the Jefferson Island salt dome. Extensive roof failure was occurring at 396 m (1300 ft) ii the third level. SCM design principles in creased the room size from 24 to 49 m (80 t( 160 ft) on the fourth level at a depth of 457 m (1500 ft). This unprecedented expansion of room width was first questioned and later ap¬proved by MS HA, which expressed satisfaction in seeing the improvement documented by field validation data in 1973. The most recent SUM application to salt mining has been in the Michigan Basin a: Goderich, Ontario. The anticipated abandonment of Domtar Chemicals Group/Sifto Salt Division's deep operation in bedded sale was prevented by a multi-year SCM implementation. The success of SCM in dry mining[lecc] to its application to solution mining of salt This adaptation of the method is now being implemented in bedded salt at Fort Saskatchewan, Alberta by Dow Chemical Co., and in St. Clair, MI by International Salt Co. Application of SCM to solution mining in a salt dome is proceeding at Napoleonville. LA by Dow Chemical. The same technology has also been applied to cavern design for the Louisiana Offshore Oil Port (LOOP), and the compressed air energy storage (CAES)

Jan 1, 1989

By Mahiyar Nasarwanji, Jonathan K. Hrica, Jonisha P. Pollard, Lydia M. Kocher, Brianna M. Eiter

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and non-fatal injuries. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the Mine Safety and Health Administration (MSHA) between 2010 and 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84% involved the workers not using fall protection, fall protection not being provided, or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment, or working near highwalls. In most cases, a single, basic, corrective action (e.g., using fall protection) would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate, and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

Minerals are fundamental to the U.S. economy, contributing to the real gross domestic product (GDP) at several levels?mining, processing and manufacturing finished products. The estimated growth rate for the real GDP of the United States was 2.1 percent and the nominal GDP was about $13.8 trillion in 2007 (Table 1). The prime interest rate decreased to 7.25 percent in December from 8.25 percent at the beginning of 2007, reflecting actions taken by the Federal Reserve Board to counter financial difficulties surrounding subprime mort-gages. Delinquencies on subprime mortgages increased throughout the year, affecting not only the delinquent home owners but also financial instruments invested in mortgage-backed securities. The average contract mortgage rate for the purchase of previously occupied homes in the United States was 6.35 percent in November; a slight decrease from 6.37 percent in January but still greater than 5.34 percent reported in July 2003, the lowest rate in the past five years. With the tightening of credit, the seasonally adjusted annualized rate for new privately owned housing starts declined 27 percent from December 2006 to November 2007. The loss in the residential market was balanced by a 9-percent increase in nonresidential construction between January and August 2007, during which slight increases occurred in nearly all

Jan 1, 2008

By C. O. Lee

The Grand Isle Sulphur Mine is located in the Gulf of Mexico, approximately seven miles off the coast of Grand Isle, Jefferson Parish, Louisiana. The depth of water at this location is about 50 feet. The deposit is on acreage covered by oil, gas, and mineral leases which were originally issued in favor of Humble Oil & Refining Company by the State of Louisiana, and which were continued, maintained, and redesignated by the Department of the Interior of the United States, pursuant to Section 6(b) of the Outer Continental Shelf Lands Act. On September 19, 1956, Freeport Sulphur Company acquired from Humble Oil & Refining Company the sulphur rights underlying the tracts. This assignment was approved by the Secretary of the Interior on July 12, 1957. The Director, United States Geological Survey, approved Freeport Sulphur Company as Operator on July 31, 1957. Actual design began in September 1956; the first structural contract was let December 15, 1957, and offshore erection began in June 1958. The initial phase of construction will be completed and production started in early 1960. The estimated total cost of the project is $30,- 000,000, of which $8,000,000 is the extra cost for being in the Gulf of Mexico.

Jan 1, 1959