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By H. L. Monroe

Meramec Mining Company, owned 50% by St. Joseph Lead Company and 50% by Bethlehem Steel Corporation,- is engaged in the mining, concentrating and pelletizing of iron ore from the Pea Ridge Mine which is located in the rugged, wooded Missouri Ozarks about 15 miles from the town of Sullivan or 75 miles southwest of St. Louis. The orebody was delineated in the middle 1950's by the St. Joseph Lead Company during the Company's intensive exploration program to discover new lead orebodies to replace the declining reserves of the famous Southeast Missouri Lead Belt. An airborne magnetometer survey was run by the U.S. Geological Survey, the Missouri Survey and several mining companies, (of which St. Joseph Lead Company was the principal supporter). The survey was published in 1950 and disclosed an anomaly in the vicinity of Pea Ridge. In 1950 test drill holes disclosed that under some 1300 feet of sediments there did exist an iron deposit of probable commercial significance. No further action was taken until 1956 when additional drill holes confirmed beyond reasonable-doubt-that this was a major iron ore discovery.

Jan 1, 1965

By O .. G. Sharrer

Loading mechanically has of late become the most widely discussed subject in connection with coal mining and has even equalled. the discussion of safety measures as a topic of interest. The subject has been discussed in the various mining journals and by well. informed persons at the Mining Institutes, so it would appear; that all has been said that can be said until further experiments bring out new lines of discussion. It is, therefore, not the intention to present this article as a technical discussion of the subject of mechanical loading as a whole, but rather as a plain talk on machines with which the writer has had personal contact. In 1919, during the first period of post-war depression, a Pennsylvania coal company employing union labor became interested in the possibilities of mechanical loading with the hope of reducing their mining costs, which were and are yet too high to meet competition from the non-union fields of Somerset and Westmoreland counties. Of several loaders presented for their consideration the model of the Joy loader shown by Mr. Joseph F. Joy, seemed to hold the greatest possibilities, and after extended study, the management decided to invest in a machine of this type. A machine was built, which as far as the writer knows was the only one of its type ever put on the market. This machine arrived at one of the mines early in 1920 and was put to work immediately. It was a forerunner of the present 4-BU and 5-BU types, but differed from them very radically as to design. In general the machine consisted of the familiar Joy gathering arms and a short conveyor which discharged into a steel tank which held about four and one-half tons of coal. This tank was emptied by a second conveyor which placed the coal in the mine car. The object of this conveyor tank was to provide storage room while changing cars and to allow the machine to load on the entry while the room was short. This plan was very efficient and from our experience was worth retaining, but has been abandoned by the Joy Company on account of its making the machine unwieldy. The whole machine was mounted on caterpillar tractors which were driven by two 10-H.P. Westinghouse series wound motors, each having its own controller, the controllers being arranged in tandem so as to be operated by the same handle. This very ingenious scheme which is shown in Figure 4, was supposed to make it possible to steer the loader by the controllers. By swinging the handle one way both motors moved forward, by swinging the handle the other way both motors moved backwards and by twisting the handle as shown by arrows, one motor moved ahead and the other back, thus causing the machine to turn. This scheme proved a failure as the loader was too temperamental and erratic in its operation. After Mr. Joy, himself, narrowly escaped serious injury, this device was taken off and the controllers manipulated separately. This system never proved satisfactory and was abandoned' for

Jan 1, 1925

By Sam Rosenblum

The anomaly ratio is obtained by dividing the analyzed value of an element by the anomaly threshold value of the element. The sum of anomaly ratios for all anomalous elements in a sample may be compared with similar sums for other samples, so that the samples having the greatest anomaly-ratio totals can be recognized easily. In partial or full-suites-of-ore-elements the use of anomaly ratios is more meaningful than analyzed values because the ratios quickly indicate anomalous elements and call attention to samples and localities that should be investigated.

Jan 1, 1980

Australians have always been great travellers but, traditionally Australian companies have been very conservative in contrast to more daring individual Australians. During the 1960s, '1970s and 1980s, the Australian companies spent much of their time exploring in Australia. It was only some of the major companies like CRA and BHP that had explored in places like Bougainville and Chile. However, during the mid-1980s some of the smaller companies started looking beyond their shore towards other opportunities in other countries. Why did they do this? Were they pushed or did they jump? And where did they go?

Jan 1, 1996

By Donald R. East

For many years there has been increasing pressure on mining companies, not without some justification, to design tailings storage facilities which guarantee some degree of protection against process solutions entering local groundwater and surface water flows. A fairly straightforward approach to achieving this has been to design conventional water-retaining type structures, and this has often been reinforced by the need to store large volumes of process water and seasonal run-off within the tailings facility. The conventional design uses naturally occurring geological barriers and a conventional embankment with possibly a grout curtain, or artificial barriers around the entire facility, using either imported low permeability soils, admixtures, or synthetic liners. While these approaches may achieve the primary objective of minimizing seepage, various other factors should be considered. Firstly, by depositing the tailings slurry in a sub-aqueous manner, the tailings, especially if relatively fine grained, will settle to very low densities and little or no on-going consolidation may occur over the operating life of the mine, There have been many cases where measured pore pressures within the tailings mass equal the total overburden stress, i.e., no consolidation and no strength, many years after decommissioning.

Jan 1, 1998

By Gunnar Nord

Introduction ??Atlas Copco has customers both amongst Miners and Contractors ??We believe that the contractor's approach to tunnelling is worthstudying ??For a tunnel contractor the incentive is speed as ?30 % of the costs are material related ?70 % of the cost are time related ?A tunnel contractor favours utilizing of the face ?A miner favours utilizing of the gear ??Statement; In mining, a long term average advance rate of more than 10 m / day can be achieved with the excavation techniques availabletoday

May 1, 2009

By Arsenio Enriquez, Adrian Deneys

"Rio Tinto through its subsidiary Kennecott Utah Copper Corporation (KUC) and Praxair have implemented the CoJet® gas injection system for copper anode refining. The system provides the capability to melt on average 60 to 70 tons of scrap copper per heat (with acceptable NOx emissions). The system has demonstrated the potential for tuyere-less sulfur and oxygen removal using coherent jet technology.This paper describes the process concept, system development, laboratory testing, implementation, current operation and ongoing developments."

Jan 1, 2009

By Clyde Wyman

THERE has always been a question as to the extent to which oxidizable alloys might he recovered from charged scrap in the, acid electric furnace. While qualitative information was not lacking, the quantities that might be recovered and the conditions best suited for such recovery were not clearly defined. The present investigation was carried out to determine the efficiency of alloy recovery from residuals contained in the bath, especially in regard to the recovery of vanadium. A series of 24 heats was produced at the Burnside Steel Foundry Co., including medium manganese-molybdenum-vanadium, manganese-chromium, and grade B steels, in which vanadium recoveries from the residual vanadium were investigated. Recoveries of other alloys were also studied from the accumulated data. These heats were produced in a 5-ton acid-lined electric furnace. The analysis of metal and slag samples and the micrographs were prepared by the Research Laboratories of the Vanadium Corporation of America. In addition to the vanadium contained in the scrap charge, ferrovanadium was added to the charge and to the molten bath to bring the residuals up to the desired level. Vanadium pentoxide (V2O5) in one series of heats was added to the bath after meltdown, for the same reason. In addition to the general furnace practice, the slags of these various heats were treated with coke breeze, Ferrocarbo-S (silicon carbide), and aluminum dross to determine the effects of different reducing agents upon the alloy recoveries and upon the final product.

Jan 1, 1947

It may at first sight appear somewhat presumptuous for the writer to attempt to discuss a subject in which he cannot pretend to possess any special scientific training; but a sufficient apology can surely be found in the fact that a very large percentage of the accidents from explosives occurring in metalliferous mines is traceable to the ignorance of the characteristics of these compounds by the miners who have to handle them, and to their deliberate disobedience of the rules laid down for their guidance by the manufacturers, the government regulations, or the special rules of the mines.The only method which promises any possibility of improvement upon these conditions is to substitute reason and understanding for the rule-of-thumb principle which says "you should do this" or "you should not do that." In the one case his own knowledge and intelligence enables the miner to avoid any dangerous practice in the other his inclination prompts him to do anything which will save time, provided he is not found out or at best trusting to his memory to tell him what is dangerous, without the reasoning which makes that memory easy.Another evil of rule-of-thumb knowledge is that, from its very nature, it prevents adaptability, and so we find that old miners, who learnt blasting in the days of black powder, cannot understand why high explosives do not require heavy tamping, or because copper bars are permitted in tamping powder they should not be used with other explosives...

Jan 1, 1903

By Jason Berenyi

Presentation Overview ? What is Potash? ? Where are the potash deposits? ? Current potash mines ? production, capacity and planned upgrades ? Saskatchewan Saskatchewan?s Potash Production Potential s ? Current Status of Potash Exploration ? Increasing Demand for Potash ? Saskatchewan global role

May 1, 2009

By L. H. Marshall

MALLEABLE-IRON castings frequently are made brittle by hot-dip galvanizing. The castings may be and usually are perfectly normal before the hot-dip treatment, in that they will stand a remarkable amount of distortion and punishment before fracturing, yet, after galvanizing, a single blow with a hammer will often cause a break. One such casting broke when accidentally dropped on a concrete floor. Such weakness causes galvanizers to view malleable cast iron with misgivings, and, in turn, is a source of worry to the manufacturer of the castings. It is felt, therefore, that a practical method of overcoming this embrittlement, a method that has already been used on several thousand tons of castings, will be of general interest. The purpose of this paper is to describe this immunizing process. DEVELOPMENT OF THE PROBLEM In the early days the trade was not much concerned with the finish of the castings and in most cases the only protection given to the parts placed in service was a coat of paint. It was soon found that this form of protection was inadequate and the user demanded a better type of rustproofing. In compliance with this demand, the use of zinc for coating gradually spread until it became general practice. More than half of all the zinc produced today is used for coating iron and steel, and, in spite of the recent use of cadmium and chromium, zinc coatings are still recognized as among the best general rust inhibitors for atmospheric exposure.

Jan 2, 1926

[Participating Scholarship Colleges and Universities 144 Andalex Resources, Inc 91 Behre Dolbear & Company, Inc 93 Canyon Fuel Company, LLC 92 Big Sky Coal Company 114 Commercial Testing & Engineering Company 96 Continental Conveyor & Equipment Co 97 Copper Mountain Resort 108 Cove Shoe Co., Inc 110, 111]

Jan 1, 1999

In this U.S. Bureau of Mines report, in situ vat leach mineral recovery system concepts are described and cost compared with conventional mining and pad and autoclave leach processing systems. In the proposed systems, leachable ores are enclosed in place in reagent-impermeable in situ vat constructions. The ores are then rubbled and flood leached or flood oxidized and leached. The in situ vats are called stope leach or stope autoclave vessels. The report also proposes ore body-adjacent in situ vat constructions containing rechargeable processing stopes. A series of ore body-specific, innovative, and conventional mineral recovery systems case study designs are described and prefeasibility level costed. Based on a comparison of these prefeasibility level cost estimates, the proposed systems are determined to be economically competitive with conventional min¬eral recovery systems. The in situ vat leach mineral recovery systems concepts for leachable and refractory ores are developed around the drill-split narrow-vein and longwall mining methods described in part 1 of this Information Circular series.

Jan 1, 1995

By Thomas W. Wälde

BACKGROUND Foreign investment has been a major factor in bringing about the substantial mining industries of Chile, Peru, Bolivia, Venezuela, Brasil and Guyana. But economic nationalism and sentiment against foreiqn domination of vital national industries grew in the 1960s and most major mining projects were transferred into state owner ship. Among the state mining enterprises formed were CODELCO - Chile, MINERO-PERU/ CENTRCMIN - Peru, CCMIBOL - Bolivia (in 1952), Hierro-PERU, GUY-BAU/BIDCO - Guyana, etc. New investment during that time was discouraged because it was subject to the restrictive conditions of the investment regulations of the Andean-Pact, a grouping of Chile, Bolivia, Peru, Ecuador, Venezuela and Colombia. The philisophy was that mineral resources were to be developed exclusively by national enterprises. Essential foreign inputs had to be acquired "depackaged" as separate purchases of equipment and technical assistance services. As a result of the worldwide economic recession which hit the mining industries in 1980-1982, many projects that were viable in 1970 were not developed by the new state enterprises due to lack of capital, managerial and technical abilities and due to problems with marketing. As a consequence of the long-term decline of metal prices, governments experienced difficulty in getting investment organized through national or foreign enterprises and have had to face up to the trade-offs between national control and active mineral development. A change has since taken place in governmental policies. The 1981 Peruvian mining law, the 1982 mining law of Uruguay, the 1979/1980 mineral promotion laws of Argentina, all witness the gradual shifting of emphasis from restriction to promotion. The investment rules of the Andean Pact have been progressively softened through national regulation and today are more or less irrelevant. Nationalizations and forced renegotiations have not occurred in the last few years. Countries have gone to great lengths (without much success) to re-attract foreign investment on terms that accommodate the political sensitivities of the South American countries and the practical requirements of investors and financiers. For this analysis, three contracts have been selected which reflect this accommodation in three South American countries, where miner a1 production plays a major role in the national economy. These con tracts reflect both the attitudes and traditions of the individual countries, but also mark the shift in mineral investment policies that has taken place. EL INDIO AGREEMENT The 1977 investment agreement between Chile and St. Joe Minerals marked a dramatic relationship between Chile and foreign mining investor s. In Chile, mining of copper has played a major role in the country's history. Large scale copper mining was initiated and developed by Kennecott and Anaconda. The nationalization of these two companies under the Allende government in July 1971 started a wave of nationalizations of foreign-held mining and petroleum operations since then in many parts of the world. The military government supported the new Chilean state mining companies ((30DELCO and ENMI) , but it also attempted to accelerate mineral development by prom ting foreign private investment, thus reversing the nationalistic policies followed by the Allende and the preceding Frei government. The new policy by the military government is expressed in Decreto-Ley 600 (1974) which governs foreign investment in Chile. Decreto-Ley 600 is

Jan 1, 1985

By B. F. Oliver, C. W. Haworth

Pure tin and Sn-0.5pct Pb ingots have been frozen unidirectionally from the base. For quiescent melts that were initially undercooled, a transition from lower eqlciaxed structure to an upper columnar structure is found in the alloy ingots. Columnar to equi-axed back to columnar transitions are observed in superheated alloy ingots, but no such equiaxed band is observed impure tin. The reproducible equiaxed band is associated with a thermal undercooling followed by a recalescence. This undercooling is <5"C, whereas the critical (maximum obtainable) under-cooling for both the pure tin and the alloys used is -20°C. A similar undercooling is observed at the same position in the pure tin ingots, although in this case no clear transition in structure can be seen. The structure of the pure tin ingots is either entirely columnar or mixed columnar-equiaxed. A consideration of the detailed thermal history of the ingots indicates that the ingot macrostructures are determined by the occurrence of a local therlnal undercooling in conjunction with nuclei multiplication and transport mechanisrris. GENERALLY it is found that a pure metal ingot solidifies so as to produce an entirely columnar structure. Frequently an alloy ingot is found to have a columnar outer zone and an equiaxed central portion. Early systematic work to examine the factors controlling the formation of the equiaxed structure was reported by Northcott&apos; who showed that, for copper alloys frozen unidirectionally with a given ingot practice, the alloying element influenced the length of columnar crystals and the extent of the equiaxed structure. Northcott showed that alloys with a wider freezing range more readily produced the equiaxed structure. The nucleation process can be important in producing equiaxed structures; frequently an alloy which readily solidifies with an entirely columnar structure will produce an entirely equiaxed structure when a nucleating agent is added to the melt.&apos; The formation of the equiaxed structure was attributed by Winegard and chalmers3 to the presence of constitutional supercooling; that is, a region of liquid in front of the growing solid could have a temperature below its equilibrium liquidus temperature. Thus, with a small enough temperature gradient in the liquid, it was suggested that the presence of constitutional supercooling may be sufficient to bring about the nuclea-tion necessary for the formation of an equiaxed structure. Although this explanation is plausible, and may be relevant in many ingots, Walker has described an experiment&apos; for which constitutional supercooling seems to be an unlikely cause of nucleation. A Ni-20 pct Cu alloy, repeatedly undercooled more than 50"C, was crystallized and found to show the typical colum-nar-equiaxed structure. The separation between the liquidus and the solidus for the alloy is 40°C. Thus, in this experiment the nucleation required for the formation of the equiaxed structure must have come about in some other way than by the nucleation catalysis constitutional supercooling hypothesis. Chalmers has suggested more recently5 that nuclei (in a typical ingot) are present immediately after pouring and are prevented from redissolving by the constitutional supercooling effect. More recently Uhlman, Seward, Jackson, and ~unt&apos; have shown direct evidence using ice and organic materials that freeze dendritically that the "remelt mechanism" may be an extremely effective crystal multiplication process during the freezing of ingots under conditions involving dendritic growth. JSlia" experimentally demonstrated the detachment of dendrite arms. chernov14 has analyzed the dendrite arm detachment process as a coarsening phenomena driven by the minimization of interphase area. Katta-mis and ~lemings" working with undercooled steel melts give evidence supporting this mechanism. Mechanisms of dendrite arm detachment such as those assisted by convection are believed to be the origin of the macrostructures obtained in this study. This study makes no attempt to distinguish the relative contributions of these mechanisms. The object of the present work was to obtain accurate temperature measurements during the solidification of an ingot and to correlate these measurements with the formation of equiaxed grains in the resulting ingot structures. Similar previous work is very limited. The measurements carried out by Northcott are neither sufficiently extensive nor sufficiently accurate for any interpretation. Plaskett and winegard7 carried out experiments on A1-Mg alloys in which they observed values of the temperature gradient, G, in the liquid and rate of freezing, R (for a given alloy solute content Co), at the transition from a columnar to an equiaxed structure. They reported that equiaxed crystals were produced at values of G/G approximately proportional to the solidus composition. Similar experiments using Pb-Sn alloys carried out by £111011" showed a linear relation between G/R and the solidus composition. However, the thermocouples were in the mold wall rather than in the melt and, in one case, ingot surfaces were examined. There is ambiguity in the meaning of the values of G and R measured in all these experiments. APPARATUS AND EXPERIMENTAL PROCEDURE Alloys were prepared by induction melting 99.999 pct Sn and 99.999 pct Pb to form a Sn-0.5 wt pct Pb alloy in air in a graphite crucible and casting into a cylindrical graphite mold 6 in. long, 1 in. in diarn , and with a & in. wall thickness. This mold was mounted on a copper base through which cooling water could be

Jan 1, 1968

By F. Urekar, R. B. Pankhurst

"Air spaces and air gaps in an explosives column are known to allow greater distribution and cushioning of explosive energy from the rock mass. This energy distribution is enhanced if the explosives &apos; gases can be confined in the borehole for as long as possible by plugging and stemming above the air space.Power Plug is an inflatable plug which can seal a borehole at any point to separate the stemming from an air gap and explosive toe load.IntroductionThis paper will discussion-going work by C-I -L Inc. and operators of two open pit mines to study the results of using Power Plugs:I. Pit wall stability - the authors have found the Power Plug effective for wall control blasting in open pit mines.2. Selective mining of coal seams - the authors work shows the Power Plug allows mining selective coal seams by predrilling underseam waste wedges.Pit Wall StabilityWall stability in an open pit mine is essential for safety. Good wall stability can be achieved with wall control blasting techniques which cushion the effect s of the explosives charge by decoupling the charges from the borehole wall. The usual method of decoupling a charge in a large-diameter rotary borehole is to load the explosives in tubes (Fig .I) . We now believe the air deck system is effective in sea ling a borehole above the explosive charge to create an air deck within the borehole which will cushion the blast.In a linear decoupled charge, an air annulus surrounds the explosives charge and cushions the effects of detonation genera ted gases on the pit wall. In an air deck, i.e. with the hole plugged at the collar, the gases genera ted by an explosive toe load are sealed in the empty borehole column. After a period of time, these trapped gases produce radial cracking between holes along the entire length of the borehole.It is common practice to employ de coupled explosive charge columns in the borehole to limit blast damage to surrounding rock. The exact mechanism of energy transfer in such blasts, however, is not well understood. Interruption of the continuous explosive column in a borehole by means of stemming, or air decks, may also be viewed as another form of decoupled blast. Decoupling of the explosive charge from the borehole wall affects both explosive energy release and explosion pressure developed in the borehole."

Jan 1, 1988

By C. B. Manula

This report is mainly concerned with the modification and development of a users manual for the Open-Pit Materials Handling Simulator (OPMHS) developed at Penn State. Model Modifications included the introduction of a free-format input, the application of a Weibull random generator, facilities to stochastically simulate shovel-dragline operations, and routines to increase the flexibility in making truck assignments. At the same time, core storage requirements and execution times were minimized and all P.S.U. conventions were removed to allow operation on other computing systems.

Jan 1, 1976

By D. A. Elgillani, M. C. Fuerstenau

In this paper, oxidation potentials measured in the presence of various concentrations of cyanide, ferro-cyanide, and ferricyanide and ethyl xanthate at various values of pH are related to flotation response. Eh-pH diagrams are presented to show that the formation of surface ferric ferrocyanide is probably responsible for depression when cyanide is added. The influence of cyanide on the depression of pyrite with xanthates as collector has been the subject of a number of investigations,&apos;-6 and several theories on the mechanism of depression have evolved from these studies. Wark and Cox7 and Gaudin8 have suggested that the depressing effect is due to a competition of cyanide ion with xanthate ion for the surface. Cook and his colleagues9-11 have explained this phenomenon in terms of competition between hydrocyanic acid and xanthic acid. Sutherland 12 has shown that although both of these theories accurately describe the relation between pH value and cyanide addition at constant collector addition, they fail to describe the relation between pH value and the amount of collector required to cause flotation. Taggart 13 suggested that depression in these systems is due to the formation of a reaction product between ferric ion at the pyrite surface and ferrocyanide ion derived from solution. Majumdar4,6 has attempted to prove this hypothesis by measuring the contact angles of pyrite in the presence of 25 mg per liter ethyl xanthate and different concentrations of potassium ferrocyanide and ferricyanide. In all cases the contact angles were quite high up to pH 10. These results indicate that pyrite should not be depressed by either potassium ferrocyanide or ferricyanide. In view of these facts, Majumdar has assumed that the compound Fe(CN)2 forms at the surface. Gründer and Bornl4 have stated that depression may be due to the formation of the compound K2Fe(II)Fe(CN)6 at the pyrite-solution interface. This compound is thought to be an interaction product between the K2Fe(CN)6-2 ion from solution and the Fe++ ion at the pyrite surface and, accordingly, K4Fe(CN)6 should depress pyrite at least as effectively as KCN. This was proven experimentally, but there was no simple relation between the depression of pyrite and the concentration of either KCN or K4Fe(CN)6 in solution. In view of the many mechanisms that have been proposed for pyrite depression by cyanide, it is apparent that a clear understanding of the phenomena occurring in these systems is lacking. One reason for this may be the fact that the species responsible for pyrite flotation in the presence of xanthate is not the xan-thate ion but rather dixanthogen.15 Since the oxidation of xanthate to dixanthogen is dependent on the oxidation potential of the solution, it would seem that knowledge of these potentials would be a requisite to understanding the pyrite-xanthate-cyanide system. It is the object of this paper to measure both the oxidation potential and pH of the pyrite systems in the presence of various concentrations of cyanide, ferrocyanide, and ferricyanide and xanthate and to relate these values to flotation response. EXPERIMENTAL MATERIALS AND &apos;TECHNIQUES In the experiments discussed here, pure potassium ethyl xanthate was used as collector, and reagent grade potassium cyanide, potassium ferrocyanide, and potassium ferricyanide were used as depressants. Reagent grade HC1 and KOH were added for pH adjustment. Conductivity water, made by passing distilled water through an ion exchange column, was used in all experimental work. Two natural samples of pyrite were used in the investigation. Sample preparation for flotation included dry grinding with a mortar and pestle and sizing the product to 100 x 200 mesh. Prior to flotation, a 0.75-gm sample of pyrite was added to a solution containing a known amount of depressant at the desired pH value, and the system was conditioned for 4 min. Following this, a known amount of collector was added and the system was conditioned for another 4 min. The pH — termed flotation pH - was measured; the pulp was transferred to a Hallimond cell, and flo-

Jan 1, 1969

By John W. Graham

To start my talk, I thought it might be helpful for us to define the term "aggregate", so I went to the dictionary. Webster has several listings under "aggregate", and I found the following: "1. A mass or body of units or parts somewhat loosely associated with one another." Well, I didn&apos;t like that term "loosely" so I read on. "2. Crystals of one or more kinds of mineral or rock fragments." That sounded better, but I still read on. "3. Any of several hard inert materials used for mixing with a cementing material to form concrete or mortar." That sounded even better, but it should be a little broader. So I would like to define "aggregates" for you as follows: "Hard, inert fragments of rock or minerals used alone or with cementing agents to form products essential to nearly all types of construction." Usually aggregates are sand, gravel, or crushed stone, but other minerals such as clay or shale can be heated and become aggregates. What are some of the construction uses? Well, we&apos;ve already mentioned concrete, as used in streets and highways, sidewalks and parking lots, airports and all kinds of building construction, not to mention bridges and swimming pools, and docks and breakwaters, just to list some of the uses. Our way of life couldn&apos;t exist without concrete. And you can&apos;t have concrete without aggregates,

Jan 1, 1977

By John G. Payne

The Pebble deposit contains three contiguous zones. In the Pebble West zone, granodiorite stocks intrude gently warped volcanosedimentary rocks that had been intruded by diorite sills and two felsic intrusion breccias. In the Central zone, volcanosedimentary rocks are cut by diorite and granodiorite sills; the latter are genetically associated with the granodiorite stocks. In these zones, widespread potassic alteration consists of brown biotite and K-feldspar, with abundant quartz-carbonate-sulphide vein stockworks. Chalcopyrite/pyrite ratios range from 2/1 to 1/20. Diorite hosts the highest-grade mineralization, with much of it being disseminated. Patchy, later phyllic alteration is moderate and commonly depleted in copper. The Pebble East zone occupies a granodiorite stock and intruded host rocks below an eastwardly thickening wedge of barren Tertiary volcanic and sedimentary rocks up to 600 m thick. Brown biotite alteration and copper mineralization are strong, with chalcopyrite/pyrite ratios commonly over 1/1. The zone extends to a depth of at least 1200 m below surface; some drill holes bottomed in strong mineralization. Later, weak to moderate sericitic alteration removed some chalcopyrite and locally remobilized gold. The Pebble deposit has a Measured/Indicated resource of 3 billion tonnes grading 0.28% Cu, 0.32 g/t Au and 0.015% Mo (= 0.5% copper-equivalent) and an Inferred resource of 1.13 billion tonnes grading 0.30 g/t Au, 0.27% Cu and 0.015% Mo (0.55% copper-equivalent). The Pebble East zone has an Inferred resource of 2.13 billion tonnes grading 0.55% Cu, 0.34 g/t Au, and 0.037% Mo (0.97% copper-equivalent). The Pebble East zone is open to the east and to a lesser extent to the north, south, and to depth.

May 1, 2006