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By H. E. Wilborg, G. V. Henderson

This chapter deals with those sands employed by foundries for the manufacture of cores and molds used in the casting of such common metals as steel, gray iron, ductile iron, aluminum-based alloys, and copper-based alloys. Most metal is cast in "green sand" molds in which the sand mixture, consisting primarily of silica, clay, and water, forms a plastic material. This plastic material is rammed around a pattern in a split box called a flask, then the box is separated, the pattern is withdrawn, and the metal is poured. These green sand molds are broken apart when the metal has solidified. The sand is then remixed and a new mold made for the next casting. To a lesser extent silica sand is mixed with resins or oils and, after forming, the mixture is hardened by either heat or chemical reaction. In any case, the foundry mold or core is used just once before being broken up and remixed for manufacturing another core or mold. By far the greatest consumption in the foundry is of those types of sand high in silica, low in clay (under 0.5%), and occurring in numerous locations thoughout the United States. Consumption End Uses Foundry sands fall into four distinct categories: silica sand, lake sand, bank sand, and natural molding sand. Silica sand is a general term used to describe washed, graded, dried, and cooled clay-free sands which are found in many parts of the United States. They generally contain 90 to 100% silica but vary greatly in chemical analysis and grain structure. Lake sand is the sand dredged from Lake Michigan or dug from the dunes bordering that lake. Bank sand is composed primarily of silica grain but containing up to 5% clay. It is shipped in both the damp and dry state but the normal processing of bank sand consists only of drying and scalping. Occasionally two different grades of bank sand are blended prior to or during loading. Natural molding sand is a term used to describe a sand containing sufficient clay as mined to be suitable for molding purposes. Clay content may vary from 10 to 24% with the balance of the material consisting primarily of silica sand. These sands range in fineness from one peaked on the 20 mesh to one which contains more than 50% of the particles passing the 270 mesh. Lake sands are relatively coarse and are used in great quantities for the production of automotive castings. Bank sands and natural molding sands are gradually phasing out as the production of castings becomes more a science and less an art. The vast majority of foundry sands used today are those known as the silica sands and lake sands. Foundry sands are used in two basic ways. The majority are used in the green or uncured state with the balance used in the cured or set state. Green sand is grain bonded with clay and contains varying amounts of water to plasticize the clay in order to bond the grains together. Green sand is either naturally bonded or "synthetic" sand. The naturally bonded molding sands are generally found in the Hudson River Valley of New York State, Cumberland County in New Jersey, and in Tennessee and Mississippi. Synthetic sand is molding sand compounded in the individual foundry. It is made up primarily of graded silica sand, western or southern bentonite, water, and carbonaceous and/or cellulosic materials. Green sand is used primarily in making molds. The use of naturally bonded green sand has been declining for many years, primarily because naturally bonded sands are more difficult for the foundryman to find and control. Synthetic green sand, on the other hand, can be

Jan 1, 1983

By Walter Harvey Weed

THE enrichment of mineral-veins as a result of the migration of material from an upper oxidized or disintegrated part of a vein to a lower level, where it is redeposited, is now, I believe, quite generally accepted as one explanation of the occurrence of bonanzas in gold- and silver-veins, as well as that of bodies of high-grade ores in cupriferous deposits.* Vogt has called attention to the fact that there are numerous examples of such rich shoots which are " of exclusively primary character, and dependent upon the laws which governed the original ore-deposition." To this I would add that there are also other examples which are neither of primary origin nor clue to descending waters, but result from a reopening of the veins and their penetration by ascending heated waters whose metallic contents are deposited by reaction with the primary pyrite (and possibly other minerals), forming "secondary" enrichments. My studies of the copper-veins of Butte, Montana, show: That the veins there are of several ages and systems; that the older primary quartz-pyrite veins were reopened by later movements, correlated with a period of volcanic activity; and that they were penetrated by hot alkaline waters carrying copper and arsenic in solution, which were deposited presumably by reaction with the pyrite of the original vein. The enormous development of the Butte deposits, attendant upon the extraction of nearly 10,000 tons of ore a day, has revealed many facts concerning the nature and distribution of the ores. Enargite, the copper sulpharsenate, formerly a relatively rare mineral, is now found to be the chief ore of some veins,

Jan 1, 1913

By P. Barnes

(Resident Engineer, 1873-75.) SEVERAL statements have been made to the Institute, somewhat detached from each other, as to the cost of some parts of these works, but they have not included any extended description of the. buildings or machinery. The general plan of the work connected with the water supply differs, in some important details, from that which has been common either in the Pittsburgh district or elsewhere, and a somewhat extended description may be of interest to the Institute, in connection with a note of the cost of the work. The plan as a whole, and nearly all the important details, were developed by Mr. William P. Shinn, C.E., the general manager of the Company. The immediate and responsible charge of the work was in the hands of Mr. John C. Lewis, C.E., to whom had been committed all the work of this general description, including the laying-out of the whole of the foundations, the erection of the buildings, and the grading and laying down of the entire railroad system. The continuous operation of the machinery and other fixtures of these waterworks, for more than three years, has fully demonstrated the correctness and economy of the plan adopted. No casualties of any moment have befallen the apparatus, and no improvements have been suggested as important except that the gate at the river end of the conduit should have been made more completely water-tight, so that the whole length of the conduit could be pumped out dry without resort to any temporary dam in the conduit itself. In general terms the works of the Edgar Thomson Company are situated on a plateau, about 52 feet above the low-water level of the Monongahela River, and about 2000 feet from its bank. The site of the works is bordered on one side by Turtle Creek, a small stream which drains a considerable area of coal mining territory. This creek is about 100 feet from the group of buildings which have been erected, but it flows into the Monongahela River at a point, about 1200 feet further up than that selected for the entrance to the water-works conduit. It was ascertained by analysis that the water in the creek contains an important percentage of sulphate of lime, while the water of the river is of unusual purity, in respect of any salts

Jan 1, 1879

HeRbert A. MeGRaw, San Luis de la Paz, Guanajuato, Mex. (communication to the Secretary*) :—Although Mr. Bordeaux prefaces his paper with the statement-that it is a general outline of practice in the Republic, many of his statements seem to be made from the view-point of a particular case, which does not always agree with general practice. For the purpose of calling attention to some of these variations, I respectfully offer the following comments: The operation of crushing and grinding is performed by so many different methods and systems that it is useless to select any one as the standard. However, primary crushing in rock-breakers followed by stamps is thus far so general that it might be so classified. Whether or not it is the best way, is open to question. Regrinding may be performed by any of the various types of Chilean mills, Huntington mills, or similar machines, or the material may be taken directly from the stamps and delivered to the tube-mills. Mr. Bordeaux's statement that " the slimes can be treated only by decantation; the new Butters slime-filter, as used in Nevada, does not seem to be successful with silver-ores," is surely an error. All over Mexico many of the purely silver-ores are being successfully handled by the Butters or similar filters, such as the Moore and the Burt filters, and a letter to the manufacturers of these filters will undoubtedly bring a list of the silver-ores now being successfully treated in this way. The statement that crushing silver-ores in solution is impossible is equally erroneous. Most modern mills crush the ore in solution, in some cases containing as much as 0.12 per cent, of KCN. I cannot for the moment recall any modern mill in Mexico which does not follow this practice. There may be some reason for it in particular instances, but, generally speaking, the practice is to crush in solution. Care in installation avoids any mechanical loss of cyanide, and the chemical loss is so small as to be negligible.

Jan 1, 1910

Jan 1, 1945

E. R. Buckley, Flat River, Mo. (communication to the Secretary*) :—Some statements in the paper of Mr. Keyes relative to the nature and formation of the Ozark lead- and zinc-deposits seen1 to me erroneous and misleading, and I respectfully present the following criticisms, placing Mr. Keyes's original statements in quotations. Referring to the Ozark dome: (p. 192.) "It is a region that has been repeatedly upraised and planed off, until in the middle portion the oldest known rocks only are exposed." Does he mean that the St. Francois mountains, which have always been considered as lying on the eastern flank of the Ozark dome, are the middle of the dome ? Or does he mean that the Cambrian rocks of the generally-accepted middle are the oldest known rocks ? Certainly not the latter, and if the former, his idea of the middle of the dome is not in accord with that of others who are familiar with the region. (p. 203.) "... the ore-deposits are definitely associated with, or localized by, geologic structures of some kind that produce in effect basins in which the underground waters are impounded, or their flow retarded." This statement does not appear to be altogether consistent with the facts, since the ore bodies of the Joplin district, as the rule, occur in those parts of the Mississippian formation which have a tendency to accel erate the flow of ground-water rather than retard it. I migh name the open, brecciated ground near Joplin, Webb City, and Oronogo as especially noteworthy illustrations. The ore-bodies, everywhere, occur in positions where there must have been a free and copious circulation of dilute lead- and zinc-solutions in the presence of reducing constituents. The inequalities in the distribution of the ore-deposits are

Jan 1, 1910

By T. L. Joseph

THE committee appointed to investigate the application of oxygenated air to the blast' furnace believes, after a careful study of the problem, that this enriched air will increase hearth temperature, tonnage, flexibility of operation, and quality of pig iron made, and that fuel consumption will be decreased. These improvements are supported by theoretical evidence; but a practical trial of the process is necessary to establish more definitely the magnitude of benefits realized. The commercial application, however, may profitably be preceded by a test on a smaller scale. A small furnace will, in general, respond to the enriched air in the same way as a commercial furnace and the magnitude of the benefits to be gained from varying additions of oxygen can be fairly well established at relatively little expense. A new experimental furnace, being built jointly by the Bureau of Mines and the University of Minnesota, at Minneapolis, will have a capacity of about 6 tons and will riot require more than 700 cu. ft. of natural air per minute. Its hearth is 36 in. in diameter and its height about 32 ft. Enough oxygen to enrich the blast to the extent recommended by the committee can be obtained from a small oxygen unit. It might even be cheaper to perform preliminary experiments with tanks of oxygen obtained from regular, dealers. A procedure in making the test that suggests itself is to start with operation on normal air; then to use blast, enriched in several steps. Systematic temperature measurements of the tuyeres, slag, and metal would reveal any changes in hearth temperature. When these changes become large enough, the burden may be gradually increased to just within the breaking point and the furnace brought back to normal, if possible, by the addition of oxygen. Such a test would show what might be expected in the way of a decrease in fuel consumption and the time taken to "straighten up" the furnace by means of oxygen. The new furnace at Minneapolis is so equipped that the furnace process can be observed from the stock line to the iron notch. We have been taking gas samples at various elevations in the furnace to study combustibility of the fuel and the reducing power of the gas. If either of these is affected by removing inert nitrogen, the change can easily be measured.

Jan 11, 1924

By J. A. Bowers

THIS investigation of the effect of bottom shape and life on slag volume was carried out in two Lectromelt top-charge furnaces whose rated capacity is 1000 lb per hour. Unfortunately, just as the work [ ] was started, our steel tonnage was reduced approximately one half, therefore we did not accumulate enough data from which to draw any definite conclusions. Furthermore, the life of the linings in these furnaces was greatly decreased by intermittent operation, which was a further handicap in making a study of this kind. The weight of the heats from which the data were taken varied 1200 lb but all the information was corrected to the standard weight charge for these furnaces of 4500 lb. Almost all the heats were plain carbon; a few contained a small percentage of added copper.

Jan 1, 1947

By G. J. Harmsen

is shown that in any isotropic porous medium there is a fixed ratio, : , between the numerical valrles of the total pore perimeter per unit of cross-section and the specific surface area per unit of bulk volume. The consequences of this fact on the use of the concept "hydraulic radius" in the case of porous media are examined. The validity for consolidated sands of Kozeny's rela- tionship and of the formula derived by Carman for capillary rise are discussed. INTRODUCTION In the course of time several quantities and relations have been put forward in order to describe the texture of a porous medium and the flow of fluid through it. Among these relations the so-called Kozeny formula and a formula for capillary rise, for both of which Carman',' has given a derivation, will be specially considered here. These relations are of a semi-empirical nature and the derivations must be considered to have a heuristic significance only. For unconsolidated mate-

Jan 1, 1956

In the 100' years since AIME was founded in 1871, the Institute has issued a great many publications in a variety of forms: periodicals, Transactions volumes, and special volumes or books. The following is a brief history of AIME publishing with some suggestions for proper referencing. TRANSACTIONS AIME Transactions volumes have been numbered consecutively since No. 1 was issued in 1873, including papers for the period 1871-1873. One or more volumes have been issued each year and may be divided into three general time periods: General Volumes (1873-1927), Volumes classified by subject matter (1928-1949), and the present practice, begun in 1949, of issuing three volumes per year, one each in the fields of mining engineering, metallurgy, and petroleum technology. The broad divisions of subject matter in each of these volumes correspond to the technical areas of the three constituent societies of AIME. AIME's Technical Publications, usually designated by TP number's (until the change in numbering system by the Society of Mining Engineers in 1958), may, with some exceptions, be referenced to an AIME Transactions volume. Reference to a specific volume, rather than paper number, is the preferred reference, since the volumes are the form of publication most commonly available in libraries. In many cases, over the years, the Technical Publications may also have been available in some other form, either as separates or in a periodical. General. Volumes (Vols. 1-78, 1873-1927): Until 1927 all papers eligible for Transactions were published in general volumes with no systematic attempt made to segregate the material on the basis of the technological fields to which the papers related.. One volume per year was issued from 1873 until 1912; from 1912 until 1927 from two to four volumes were issued annually. In addition to the Transactions papers, these volumes carried some of the proceedings of the business meetings of AIMS. Subject Volumes. (Vols. 79-183; 1928-1949): The material for these volumes was segregated according to subject matter, and up. to seven volumes were issued a year. In the latter part of the period, from 1934 on, there was one volume each' year for the Petroleum, Institute of Metals, and Iron and Steel Divisions and-the remaining papers were grouped in various ways and is sued whenever sufficient numbers of papers had accumulated: The subject volumes containing mining engineering papers are listed in Table 1. The volumes for the period, 1936-1949 are included in this Cumulative Index. Each of the Transactions volumes carries on the binding the year of publication; this date does not give an indication of when the papers included were originally presented at meetings. The contents of the volumes usually list the meetings at which. the papers were presented. Not all papers from a given meeting necessarily are in one Transactions volume. Some of the earlier volumes do not have a number on the binding or within the volume. In 1934 numbers" were assigned to all Transactions volumes, commencing with the 1871-1873 volume as No. 1. Many of the papers published [ ]

Jan 1, 1972

By J. Wyn Prior

The seismic refraction technique is probably the most popular geophysical method of bedrock profiling in geotechnical site investigations but is somewhat restricted by the inherent assumptions in the method. This paper describes how Hales' method of profile interpretation is modified to overcome the assumptions of increasing velocity and layer thickness with depth when only first arrival data is available. A further expansion of Hales' method enables presentation of refraction data in a form whereby bedrock features, such as changes in velocity, relief and dip in particular, are more readily recognized. Characteristic curves of the more common bedrock features are presented as an aid to bedrock feature recognition.

Jan 1, 1979

Would you briefly describe how you chose the minerals industry and reflect upon some of your earliest experiences? I wish that I could say that I had a well-formulated career plan early in life and that mining engineering was always foremost in it, but I cannot, In fact, I was quite indecisive before I finally chose my life's vocation. But in another respect, I am glad my career unfolded in the manner it did because it gave me a better insight into advising others on career opportunities. Probably the greatest problem confronting our youth, and the one I find preys upon their minds the most, is their inability to select a career path early in life. This indecision frequently has a deep psychological effect upon them and they become down on themselves. Therefore, it fortifies them somewhat to learn that others who have become successful in their careers had difficulties choosing a career path early in life. However, while assuring young people that an early choice is not absolutely essential for success, I caution them to work toward as early a decision as possible.

Jan 3, 1979

By B. Stas, L. Siska, L. Dlouhy, A. Skrabis

The basic research program of the Scientific Coal Research Institute at Ostrava - Radvanice into the problem of geophysics has been influenced by the specific nature of present urgent geo- physical problems in mines and directed to attain higher grade of effectiveness, safety, and overall economy in mining activity. The research has been divided into two basic trends: Seismoaccoustic research deals with questions pertaining to safety in mining especially when work is in coal seams under "heavy roofs", i-e., thick beds of sandstone prone to rock bumps and characterized by caving. Methods have been developed with the definite aim to determine the time and space prognosis of critical states of tension in the rock mass when stability is disturbed as a result of mining activity. Seismic research is directed towards the determination of detailed structural and tectonic elements of the internal geological formation of the Carboniferous rocks, the establishment of continuity or tectonic faulting of coal seams, and the evaluation of magnitude, shape, and time changes in the rock mass surrounding the mine workings. The measurements have been applied either from the surface or in the underground workings according to the specific nature of individual problems. Satisfactory results have been obtained in some branches of this research, other branches being still in the stage of development. Remarkable results have been achieved in the development of seismoaccoustic methods designed to establish the time prognosis of dangerous dynamic phenomena accompanying the process of strata deterioration above the worked longwall face. One of the most

Jan 1, 1971

By Charles Kumke

THE "slot" system of mining in use at the Golden Queen mine, Mojave, Calif., does not involve any new mining methods. It is, how-ever, a, new combination and adaptation of several stoping systems in common practice. The first plans for stoping operations at the Golden Queen mine called for ordinary shrinkage stopes. The hanging wall of the vein, where exposed, is a very hard felsite with a dip varying from 50° to 70°. The vein itself is quartz, shattered and fractured enough to make it easy to drill and blast to a clean hanging wall. There is no well defined footwall. The footwall limits had to be determined by assays as the metal content faded out into the felsite. Two shrinkage stopes, each approximately 200 ft. long, were laid out and started on the 200-ft. level. One of these stopes, varying in width from 8 to 18 ft., was carried on up to the top limits of the ore, approxi-mately 120 ft., without a break in the operation. The shrinkage system proved entirely satisfactory and low costs resulted from-this operation. In the final drawing of this stope, two timbermen followed down on the ore, scaling the hanging wall clean of small fragments and placing an occasional long stull from foot to hanging wall where it was deemed necessary. Few such stulls; however, were required. The hanging wall stood up very well until the stope was entirely emptied of ore. Waste fill was then put into the stope by the glory-hole method, through a waste raise that had previously been run to surface from the middle of the stope. The second shrinkage stope ran into difficulties about 35 ft. above the sill floor. Up to this point the maximum width of the ore had been about 15 ft. The ore suddenly widened into the footwall to a distance of 40 ft. in the north end of the stope. In extending the stoping operations over this width, it was soon found that the vein material would not arch and support itself. Drilling in this end of the stope was then entirely too hazardous, and all operations were stopped. The ore was drawn through the chutes below as rapidly as possible and as soon as the stope was entirely

Jan 1, 1937

By Rikuro Otsuka

TITANIUM is attacked slowly by hydrochloric acid," and corrosion rates decrease with time of exposure.' This behavior is due to the formation

Jan 1, 1958

By Walter S. Landis

The earliest example of attempting to form finely-divided materials into larger masses for better adaptation to commercial use mas probably the briquetting of peat and lignite-waste at Paris by the use of a clay binder. It was from this attempt that our word briquette has arisen (Fr. la brique), the formed masses being shaped similar to ordinary bricks. This term does not, however, lend itself to the many shapes of such formed material as are now being produced, as few of them, aside from some of the European brown-coal products, bear any resemblance to the shape of that well-known article. The

Jan 1, 1913

By T. C. Rao

Oil agglomeration experiments were carried out on coal fines to study the effect of process variables such as pulp density, bridging oil dosage and intensity of agitation on (i) size distribution and (ii) yield of agglomerated product. It has been observed that the growth of agglomerates follows a self-preserving behaviour and using this, a characteristic curve has been derived. This curve has been found to be independent of the process variables. It has also been noted that the growth of agglomerates follows second order kinetics. In an attempt to model the process for predicting the size distribution and yield of agglomerates at different levels of the variables, the cumulative 50 percent of the agglomerates passing size (d50) has been correlated with the variables (i) through the kinetic equation and (ii) directly. These equations, coupled with the characteristic curve can predict the size distribution of the agglomerates at any levels of the variables tested. The yield of agglomerates has been found to follow a definite relationship with d50.

Jan 1, 1984

By T. Sterry Hunt

I HAVE already referred to this interesting locality in the opening address, but at the request of some of the members of the Institute, brought before them specimens of the ore and the accompanying rock. The ore, which is cassiterite, is also met with elsewhere in Maine, at Paris and Hebron, but it there occurs associated with orthoclase, quartz, tourmaline, and beryl, in concretionary granite veins, which cut the micaceous gneisses of the White Mountain series. At Winslow the veins traverse an impure gray micaceous limestone, which is found in many parts of this region, and is subordinate to the same gneissic series. The veins, which are seldom more than an inch or two in thickness, are abundant through a considerable breadth of the rock, and are interlaminated with it, occupying places between the sedimentary layers, which are distinctly marked by different shades of color. Occasionally, however, they cut across the stratification for a little distance, showing that the disrupting action was not always confined to tearing the layers apart. The vein-stone consists of purple fluor-spar, and silvery white mica with quartz. In this gangue the cassiterite, nearly black in color, is disseminated in small crystalline masses, sometimes one-half an inch in diameter, and is associated with a little mispickel. I have only seen the veins as exposed at a single point, but was informed that similar veins holding the ore are met with at a distance of several thousand feet

By P. P. Reichert, L. S. Gournay, N. T. Burdine

An investigation of equivalent pore entry radii in typical samples of petroleum reservoir rock and the pore volume associated with each value of pore entry radius has been made. Theoretical discussions together with experimental procedures for obtaining pore entry radii and the distribution of pore volume with pore entry radii are presented. Experimental results on a number of core samples, along with typical distribution curves, are shown. Data on the per cent of the pore volume filled by mercury at a pressure of 1500 psi are included. The results of re-runs of samples, made possible by regenerative apparatus, show the repeatability of the data and indicate the amount of physical change in the samples by mercury penetration. Theoretical equations for calculating permeability from pore size distribution data were derived and the results of such calculations are compared with measured gas permeability data. The effect of the shape, surface area, and weight of the sample on the pore size distribution of reservoir rocks was investigated experimentally. Mercury capillary pressure curves are compared with those obtained by the porous diaphragm method using pas to displace water. Standard core analysis techniques, in general, lead to quantities which are statistical averages of the varying properties of the samples under examination. Although such statistical information has real value in predicting the gross performance of porous bodies. it fails to provide fundamental information concerning the properties of the porous medium itself or any processes which may be occurring in it. For example, a gas permeability measurement on a core sample is an indirect way of determining an average pore radius for that particular sample. Since there are many combinations of pore radii that will give the same radius. and, hence, the same permeability, no information is obtained on the pore size distribution. Furthermore, similar values in permeability do not imply similarity in other properties of a porous medium. For instance, it is possible to have two core samples with identical permeability which would have different residual oil contents at the end of an air-oil drive, or even different amounts of interstitial water. It has been recognized for some time by the petroleum industry that a determination of pore size distribution for porous reservoir rocks offered promise of increased understanding of fundamental flow processes in the porous matrix. and therefore of petroleum res- ervoir performance in general. There have recently been published several methods for determination of pore size distribution in porous materials. A report is given here of the modifications in equipment and technique required to adapt one of these methods to measurements on petroleum reservoir core samples. Although only a few correlations or applications of the method are available for presentation at this time, the technique is brought to the attention of the industry so that the opinions and experience of others with this or similar techniques may be exchanged. It seems possible that the method will have wide application in the future. METHOD There are three general methods which may be employed to measure the pore size distribution in naturally occurring rock formations. One method1 is based on experimentally determined adsorption isotherms for calculating the surface area of the porous medium. Knowing the surface area and the pore volume, a rough estimate of the pore radius can be made. Since this method depends on the thickness and uniformity of the adsorbed layer, the validity of the results would be highly questionable. A second method utilizes capillary pressure data obtained by static dis-

Jan 1, 1950

By Norman J. Gibbs, John Sroka

INTRODUCTION At the point a company decides to begin mine development and wishes to convince lending institutions that the proposed operation will return their borrowed funds, plus interest, over the terms of the loan, communications between lender and borrower are crucial. The importance of the mine feasibility presentation should not be underplayed, especially as new projects continue to increase in size, complexity, and cost. While the content and emphasis of a report to the lender will vary according to the particular project and type of debt financing sought, there is a general base of information upon which all such studies are built. THE PROJECT'S TECHNICAL ASPECTS Here, the object is to satisfy the lender that he will not be unduly exposed to technical risks as a result of the physical scope of the project. Reserves The feasibility report submitted to financial institutions should include an adequate description of the geologic setting, mineralogy, ore types, and reserves broken down into such recognized categories as proven/probable/possible or measured/indicated/inferred. Rather than a bald statement of reserves, lenders prefer to have detailed information on: History of exploration Drilling, both percussion and core, with core recovery, drill hole spacing, analyses, and continuity of mineralization Bulk sampling, with core assay comparisons Overburden, with stripping ratios Specific methodology of reserve calculation, and Geologic reserves vs. mineable reserves. As a rule of thumb, a lender would prefer to see that reserves in the proven class alone are sufficient to support operations at the design rates until the borrowed funds are repaid. (See also Schreiber above in this Chapter.) Mining The rationale for adoption of a particular mining technique should be presented as well as descriptions and justifications for: Preproduction development Preliminary mine plan, with forecasts of grades and material movements Geotechnical test work which influenced decisions Mining recoveries and efficiencies Major equipment, with type, model, rating life, spares, replacement schedules, utilization, and productivity Manpower requirements and work schedules Design assumptions Ore stockpiling and blending Environmental requirements, and Waste disposal Processing If a new ore body is to be developed or a new process used, it is important to provide details of test work, scale up, and extrapolation factors. A basic process description with a summary of the studies which justify the intended processing route should be included with the following data:

Jan 1, 1985