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By Frank W. Bowdish

Studies of sulfidization and flotation of chrysocolla involving the use of pH and sulfide ion instruments, a Zeta meter, microflotation techniques, and sensitive determinations of adsorbed sulfur have given new insight into the mechanism of the process. Factors that affect the recovery of sulfidized chrysocolla by flotation appear to be the pH at which it is sulfidized, and certain alterations of the surface that occur during aging after sulfidization. Such aging results in increased recoveries. The surface charge, as measured by electrophoretic mobility, of chrysocolla shows an unexpected negative increase as pH values are changed from 6.0 to about 4.5, and this appears to be correlated with increasing sulfur adsorption and flotation recovery over the same or even wider pH ranges.

Jan 1, 1970

By Raymond L. Zahradnik

Marco Polo reported that the Chinese used "black rocks" for fuel, and recent studies indicate that the Chinese may have used coal in small amounts for two or three millennia previously. The use of coal as a major source of energy however, did not begin until about the twelfth century, when the inhabitants of the northeast coast of England discovered that certain black rocks found along the seashore--and thereafter known as "sea soles" would burn. Since this initial discovery, coal has been mined continuously, first in England and shortly thereafter in present Belgium, France, and Western Germany, and finally in all coal-bearing areas of the world, in ever increasing amounts. The production of coal in the United States began about 1820, when 14 tons were reportedly mined. Since that time the production of coal increased steadily until about 1907, after which the rate has fluctuated between the extremes of about 400 and 700 million tons per year. Bituminous coal and lignite production was 590 million tons in 1974. Value of production was $8. 9 billion. Anthracite production was b.3 million tons with a value of $157.5 million.

Jan 1, 1975

By Howard M. Graff

The Inland Steel Company operates five underground iron mines in the Lake Superior District. The two largest of these, from the standpoint of productive capacity, are the Sherwood Mine in Iron River and the Bristol Mine in Crystal Falls, both on the Menominee Range of Michigan. It is at these two mines that we have had our principal experience with belt conveyor installations underground, .At the Sherwood Mine, which has an annual capacity of about 450,000 tons, the first conveyor belt installationwas made in 1947 when conveyors were installed in the main haulage drifts on the 1200 ft, level, It was estimated at that time that approximately 5,000,000 tons would be mined from the stopes above the 1200 ft, level and. that if all this material could be moved to the shaft by belt conveyor, the entire cost of operation, including maintenance and the amortization of the equipment, would be about $,05 per ton, which was slightly more than half of what the cost would have been by conventional tramming methods employing locomotives and cars. Now, ten years later, the 1200 ft, level is almost completely mined out and we have actually removed. 5,200,000 tons and. the average cost of transporting this material to the shaft by belt conveyor has been $.095 per ton. Since there has been a substantial increase in hourly rate of pay and also in the cost of materials since 1947, we feel that the anticipated savings were very nearly realized., The 1200 ft, level installation at the Sherwood consisted of two 36" trunk line conveyors 815 feet long and 380 feet long, respectively, deliverying ore to the shaft. These in turn were fed. by three lateral 36" conveyors which paralleled the sides of the orebody, These gathering conveyors passed under draw points to which ore was brought from the stopes by mea S of scrapers or shaker conveyors, Shaker conveyors were used for a number of years in conjunction with the conveyor belt system of haulage but it was finally concluded that with this particular type of ore, the maintenance on shaker conveyors was excessive. Therefore, more recently, we have gone back to scrapers for the shorter distances and. are using belt conveyors in the scraper drifts for the longer distances. After this belt system had been in operation for about three years, it had proved to be so successful that it was decided to proceed with the same system or. a new level to be opened up 200 feet below. Instead of sinking the shaft and driving a horizontal drift to the orebody on the 1400 ft, level, an inclined conveyor drift was started near the shaft at the 1200 ft. level and driven downwards toward, the orebody at a slope of 15 degrees. The conveyor installed in this inclined drift is 36" wide, 990 feet long, is powered. by a 100 hp motor, and is capable of delivering 300 tons per hour to the 1200 ft, level shaft pocket. It is fed by lateral horizontal conveyors on the 1300 ft? 1400 ft., and 1425 ft, sub levels. Wien the inclined drift was started, the rock was scraped from the breast directly to the rock pocket at the shaft. As the distance increased., double scraping was employed, until the advance had reached 350 feet, At this point a portion of the final conveyor was installed, with a scraper slide near the breast, T e drift was then advanced be scraping on to the conveyor until a sufficient distance had been driven to permit the installation of an additional 200 feet of conveyor. This proved to be a very efficient and economical means of moving the development rock to the shaft and obviated the need of using cars or an inclined skip way, At the present time 85 percet of tie entire mine output is being mined below the 1200 ft, level and is delivered to the shaft via the inclined conveyor. The system appears to be working as well and as economically as did the conveyor systemonthe 1200 ft, level.

Jan 1, 1958

By M. G. Schulz

Mining of molybdenum at Questa, New Mexico has been accomplished by block cave methods since August, 1983. As caving progresses, a periodic geologic evaluation is made of the rock-types present in finger raises on the Grizzly Level of the mine. The production maturity of the cave can be monitored by relating this data to geologic cross-sections through the ore body. The draw point mapping program is a simple and effective tool that is used in making draw control decisions at Questa.

Jan 1, 1985

By Edgar F. Cruft

It is sometimes said that "mines are made, and not found". I rather doubt that the exploration geologist would be overly sympathetic to that statement, and, of course, like most one-liners it is only partly true. As an explorationist who has been involved in building his own company over the last ten years, and by necessity has become a financier, I can appreciate what real grains of truth are in that statement, however. Because technical people are seldom taught financing in their basic training, and because they are usually not involved in it until at quite a senior level in their careers, the whole field often acquires a certain mystique. The engineering professions have too often believed financing is the province of the accountant or financial executive and just as we in the technical world are often too quick to bristle if the latter try to tread on our domain, the opposite can just as easily be true. Unfortunately, this is another example of a compartmentalized individual, and that is one thing the successful financier cannot be.

Jan 1, 1979

By Alvin D. Cronberg

Silica flotation with amine salts has been a commercial process for years in certain non-sulfide mineral systems. Phosphate rock and feldspar deposits are notable examples. Generally, the quartz is clean and coarse. Primary amines and imidazolines are used, usually in a mole weight range 250-300, ad often fairly impure grades of collectors are satisfactory. As the production of magnetic iron concentrates grew in Michigan, Minnesota, Canada and in foreign locations, the iron mining companies began to explore amine flotation of silica to improve these concentrates. Many of the mining companies, as well as reagent suppliers, government laboratories and university research teams, had already studied amine collectors for silica, but the application to magnetic iron concentrates presented a real commercial opportunity to apply the art. Amine flotation of silica has been accomplished by simple addition of a flotation cell, and possibly a regrind mill, at the end of the magnetic concentration process. The flotation system gave the mill operator a flexible method to control final grade caused by ore variations in the feed. It increased iron content with lower silica, which resulted in lower freight costs per unit Fe and better pellets for blast furnace use.

Jan 1, 1968

By Joseph E. Schiller

As part of the Bureau of Mines research on identification of asbestos fibers, a method was discovered for removing asbestos fibers from water. This report describes this process and its theory of operation. The surface charge of amphibole minerals in potable water was found to be negative, and in common with most other silicate minerals, the isoelectric point of amphibole asbestos fibers lies in the pH range 4 to 6. Magnesia is one of the rare oxides with a high isoelectric point of about 11. The surface of magnesium oxide will, therefore, be positively charged in water at pH 6 to 6, while the electric charge an. amphibole asbestos fibers is negative. Because of the electrical attraction of these oppositely charged solids, it was possible to remove negatively charged asbestos fibers from water by percolating water that contained suspended-asbestos through a porous bed of magnesium oxide particles. A bed of 100/200-mesh MgO was added to a glass tube with a cotton plug. Aqusous suspensions of 1 to 10 ppm cummingtonite asbestos (amosite), crocidolite, and chrysotile were percolated through this porous plug of MgO. Even though chrysotile is positively charged below pH 11, MgO is an effective filter medium for removing it. The highly basic MgO appears to cause the chrysotile to flocculate and attach to particles within the bed. Scanning electron photomicrographs indicated that essentially complete removal of the fibers from water was accomplished. Other materials tested as contact filter media and found to be ineffective or only partially effective were sand, calcite, carbon, diatomaceous earth, and cellulose. Acidic alumina collected amphibole fibers but not chrysotile fibers.

Jan 1, 1980

By Norman M. Junk

Following the wide-spread acceptance of ANFO as a useful, low cost blasting agent, studies have been made to adequately describe the physical and explosive properties of this material (1). As the quality of the AN blasting prill improved, reliability and sensitivity to initiation were greatly increased and many methods of priming were chosen from the standpoint of economics with little appreciation for the need to initiate so as to obtain the most efficient detonation. Under certain conditions, ANFO could be initiated with primers no more powerful than a No. 8 blasting cap (2). Research on primers for ANFO followed and it was demonstrated that this blasting agent was subject to extreme transient velocities upon initiation with wide variations in energy output depending upon the nature of the primer. For these reasons it was shown that powerful priming was economically justified (3). These studies helped to define the properties of an effective primer and the guides for its efficient use. In the vast surface coal mining industry, technological advances in earth moving equipment were paralleled by the development of larger and larger borehole drills (4). Even though ANM) was the major blasting agent used in this industry, investigations of priming techniques in these larger boreholes was almost non-existant. In 1962, Mr. Cleon Woolsey of Enos Coal Company disclosed to the industry that dramatic improvements in blasting production could be achieved with new priming and boostering methods (5). The research program at the Atlas laboratories was designed to explain these results and extend the study of initiation of ANFO with both high explosives and slurry explosives and to define the principles involved.

Jan 1, 1968

By Roger K. McLimans

Sphalerite in the ores is multi-banded. Based on color and textures, bands in samples separated by a few kilometers may be correlated. Darkness of color is directly related to iron content. Isotopic and fluid inclusion data indicate that temperatures of ore deposition were 225°C-50°C. The agreement between these two sets of data suggests that chemical and isotopic equilibrium were established. The salt content and hydrogen and oxygen isotopic compositions are similar to present-day values of oil field brines suggesting a similar mode of origin. Ore transport and deposition are not adequately explained by either chloride or bisulfide complexing. Necessarily, other mechanisms were involved.

Jan 1, 1979

By Chi-shing Wang

In many cases the roof strata of a bedded deposit may be considered as a composite of rock beams of rectangular cross section, whose component layers differ in thickness and may or may not be separable from each other when they are subjected to loading by their own weight. An analytical study of the behavior of such multiple-layer beams is extremely difficult owing to the heterogeneity and anisotropy of rock materials. The complexity is revealed by the fringe photographs obtained from several series of barodynamic photostress experiments conducted on various types of multiple-layer model beams of a medium-grained Bedford limestone. Further discussion on the applicability of barodynamic photostress techniques to the model study of the behavior of mine roofs in stratified geologic media is presented by comparing the phenomenological observations recorded in this investigation.

Jan 1, 1968

By N. T. Mirafuente

The device called "Dynastat" which is described in this paper provides in situ borehole measurements of dynamic and static parameters for use in a wide range of design applications. In the dynamic mode, the Oynastat allows measurement of shear and compressional wave velocities. From these velocities in situ dynamic Young's modulus and other dynamic elastic parameters can be calculated. In the static mode, the device allows measurement of load versus deformation from which in situ static Young's modulus can be determined. Information on in situ horizontal stress fields can also be estimated from the load deformation curves. In both mining and civil engineering applications, in situ measurements of material properties are indispensable for accurate evaluation of design problems. Laboratory dynamic and static test measurements in comparison to in situ measurements are often misleading due to difficulties in obtaining undisturbed samples and in accounting for effects of discontinuities, etc., for mass properties. The authors contend that among in situ borehole measurements, the method employed with the Dynastat is the most accurate and detailed technique of measurement. The Dynastat employs the crosshole method of shear and compressional wave velocity measurements and also performs as a borehole jack to obtain load-deformation relationships of materials at exactly the same location at depth in boreholes.

Jan 1, 1976

By V. J. Hucka

Coal, which was discovered in Utah in 1849, covers about 18% of the total area. Production in 1981 vas more than 14 million tons. However, some Utah coal mines are quite gassy. If longwall face technology is applied, then a release of a high volume of methane may be expected during the mining process. Investigations on methane content have been made by use of an isothermic bubble desorbometer. The desorbable methane content of 5 m3 to 16 m3 of methane per ton of coal mined has been determined.

Jan 1, 1983

By Peter I. Brooker

The semi-variogram, the basic tool of geostatistical estimation procedures, must itself be estimated from the available data. From a numerically simulated two dimensional deposit, with known variability expressed through its semi-variogram, the standard arithmetic mean estimator is used to calculate experimental semi-variograms. These are determined on a series of data sets obtained from the deposit with various sampling grids which cover different areas of the deposit and which have a wide range of available data. The orders of discrepancies between estimated and theoretical semi-variograms are determined in this idealized situation; and this provides a basis against which to assess experimental semi- variograms made on field data.

Jan 1, 1982

By A. L. Crandell

The Cortez Mining District has had a long history of mining activity dating back to 1862 as previously reported (1) (2). More recently Cortez Gold Mines (i) has operated a cyanide leach, counter current decantation (CCD) recovery gold mill from January 1969 to February 1976. This type of plant has been standard in the U.S. for treating higher grade finely disseminated gold in Carlin type ores. The mill was initially operated from 1969 to 1973 at 1520 tonnes per day on oxidized ore from the Cortez ore body. Starting in 1973, the mill was operated at 2050 tonnes per day on softer, less oxidized, high clay ore from Gold Acres which is located 13 kilometers to the west of the Cortez installation. In February of 1976 the oxidized portion of the ore body at Gold Acres was depleted and the mill ceased operation. Successful heap leaching of the lower grade portion of the ores was practiced at both Cortez and Gold Acres to supplement the milling operations. Much valuable experience was gained in the operation of these two heap leaching programs and is well described in an earlier publication (3). Releaching of the ore heaps at Gold Acres and Cortez was continued with a limited crew from 1976 to 1979.

Jan 1, 1986

By Byron M. Jones

The use of computers in system analysis is well established. Analog computers have been used for this purpose since about 1940. As the power of digital computers increased and their cost decreased, much of the analysis formerly done by analog computers has been diverted to digital computers. The mathematical foundation for system analysis was laid between the years 1700 and 1900. In the 1930?s, telephone repeater amplifiers were designed using systems analysis techniques. From 1940 to 1960 systems were analyzed using either direct simulation or LaPlace transforms. Since 1960 analytical methods have been expanded to include linear vector space theory. All of these methods are being used to analyze the dynamic behavior of mining machinery.

Jan 1, 1974

By Milton Hood

The Copper Flat Property is located approximately 6 miles NE of the small town of Hillsboro in Sierra County, N. M. (Fig. 1). Hillsboro was the center of considerable mining activity in the late 1800's and early 1900's following the discover, of gold bearing vein deposits and later discovery of, placer gold along the east slopes of the Animas Hills. The Copper Flat orebody is a porphyry type deposit occurring in a small quartz monzonite porphyry stock that has intruded the center of a circular andesite plug (Fig. 2). The primary ore mineral is chalcopyrite. By-product values are contained in gold, silver and molybdenum.

Jan 1, 1983

By Lawrence P. Bonicatto

The steel industry's increased demand for higher grade pellets has caused the pellet producers to investigate methods of upgrading their product. The Hanna Mining Company's Groveland plant is no exception. The Groveland Mine is located in Dickinson County on the Upper Peninsula of Michigan. The low grade iron deposit is a complex mixture of magnetite and hematite with chert, quartz, jasper, and various iron silicates. (1) Beneficiation is by Humphrey spirals and anionic flotation of the iron minerals. (2) A general flowsheet is shown in Figure 1. Flotation of the spiral tailings makes up about 75% of the concentrate. A minor amount of concentrate, less than 3%, is produced in magnetic circuits. The concentrate is pelletized at the rate of 1.6 million tons per year.

Jan 1, 1968

By Joe D. Mitzel

The Indian Head fine has been in existence since 1922. For over 56 years there have been North Dakota people mining coal at this same location. The area affected will fit inside a circle 5 km in diameter, and the coal is lignite. The seam thickness has varied from 2.4 m to 3.65m, and the overburden from 6 m to 30 m in depth. me Lignite coal which is being mined at the Indian Head Mine is from 15.8 x l0 6 to 16.7 x 10 6 J per kg; it has a moisture content of 33 to 38%; an ash content of 5 to 10%; and a sulfur content of from 0.5 to 0.7%. The moisture content and the fact that we crush the coal co a top size of 14 cm x 0, are two of the characteristics or the product which cause it to freeze and remain inside of the railroad cars on the slope sheets. The market for the coal initially was almost entirely local coal sales. That is, coal was sold to people in the area who used the lignite to heat their homes, stores, offices, schools, and churches. Back in the early 1920's, there were no stoker-fed boilers, or pulverized fuel boilers, as we have in today?s marketplace. Basically, all of the coal was sold as lump coal, pieces about 30 to 35 cm square, to be used in furnaces: and nut coal with a top size of about 7.5 cm to 10 cm to be used in the old kitchen cookstove. All of the coal fines, less than 5 cm, were screened out and layed onto a pile. There was no market for the smaller sizes of the lignite coal. It has been our experience that when the coal is in lumps or chunks larger than 7.5 cm to 10 cm, there is a very slight possibility of freezing. That is the chunks themselves freeze, but by their nature, they do not cling to one another or form large masses of frozen material which are difficult to remove from the slope sheers of the railroad cars.

Jan 1, 1980

By Raul A. Deju

A theoretical and experimental study was made of the surface phenomena occurring in a silicate - sulfonate system and a silicate -amine system, Experiments were conducted varying the collector concentration to examine its effect both on the total surface sorption and the rate of sorption. The results were compared to a theoretical model based on a Langmuir-type isotherm, Finally, the flotation behavior of selected silicate minerals was predicted from the sorption results and an explanation for the flotation of silicates postulated on the basis of both the theoretical predictions and experimental data.

Jan 1, 1967

By Philip E. LaMoreaux

The development of large quantities of ground water for any major use in an area is always of environmental concern to representatives of regulatory groups, citizens, agricultural and industrial users. From these concerns, state and federal congressional representatives receive a variety of impulses from their constituents and in turn begin a series of questions upon which to-base appropriate legislative actions. The kaolin industry in Georgia is substantial to the economy and the welfare of an important segment of east-central Georgia. It uses large quantities of water for processing. This constitutes an important source of income and tax revenue. Pumping test procedures to provide an accurate and efficient dewatering scheme have been developed and carried out at a number of mines in the kaolin district of Georgia. This paper highlights one such test and is directed at an assessment of the impact of this industry on ground water supplies of an area.

Jan 1, 1983