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By Alan Bauer

During the past several years, the trend to large-diameter blastholes in both open pits and underground mines along with the continuing developments in slurried explosives and delay systems has kept things exciting for the drilling and blasting engineer. This has been particularly so in underground mining, where new mining systems having lower cost and higher productivity have emerged. Crater technology has produced new large-scale methods for resisting front penetration in tar sand mining and also new underground retreat mining methods and methods of raising.

Jan 1, 1978

By Douglas H. Brown

Cadmium and other 'minor' metals in Canada tend to remain inconspicuous given the prominence of the country's massive production of other minerals. This same reality is reflected in the accuracy and deficiency of quantitative data concerning the sources of supply and demand for these metals. It is the intent of this paper to identify the nature of some of these difficulties and to reconstruct a more accurate description of Canada's production and consumption of cadmium, based on the results of recent surveys undertaken by the Mineral Policy Sector of Energy, Mines and Resources Canada and Noranda Sales Corporation Ltd.

Jan 1, 1978

By K. G. Colman

This text is intended to provide the operator and turn-key contractor with the basic data for sizing vibrating screens to be used in ore crushing plants. The basic capacities, modifying factors, etc. used in the area requirement calculations were developed empirically and modified to their present values based upon years of practical applications. It must be pointed out that screening is much more of an art than an exact science, however, the information presented here should provide for reasonably accurate screen sizing when applied to metallic ores .

Jan 1, 1978

By Robert H. Essenhigh

A stirred reactor (SR) combustion system has been developed to gather information on the mechanisms of ignition and flame propagation of coal dust under conditions similar to those found in coal dust explosion flames. The prime scaling variable considered in this study is that of rapid particle heating (between 105 and 106°K/sec) which is accomplished by means of turbulent mixing during combustion. The SR combustors tested in this study have consisted basically of spheres hollowed in the centers of refractory housings. Coal and air mixtures have been injected into the spherical combustion chambers through a single jet, two opposed jets or four opposed jets. The diameters of the jets have ranged from 0.63 to 0.22 cm. The volumes of the combustion chambers have ranged from 1.0 to 0.2 liters. The reactors have been equipped with thermocouples embedded in the combustion chamber wall as well as a thermocouple located in the exhaust gas stream. In the latter versions of the SR, provisions were made for both solid sampling and gas sampling of the reactant stream exiting from the combustion chamber. Experiments have been carried out using pulverized bituminous coal. The coal has been reacted in an SR in mixtures of air and air/nitrogen. These experiments have provided information on the mode of ignition of the coal as well as yielding information on the kinetics of coal pyrolysis through the use of SR theory. Ash tests performed on the reacted samples collected from the SR indicated that the majority of the values of weight loss percentage were between 60 and 70 percent. The percentages of weight loss were relatively unaffected by changes in temperature which varied between 1100 and 1700°K and by changes in residence time which varied between 10 and 20 millisec. Volatile matter tests performed on the samples indicated that the volatile matter left in the char ranged from 3 to 20 percent of the original content. By assuming that all the mass loss was due solely to pyrolysis with no combustion occurring at the particle surface, Q-factors for each test have been calculated. The results of these calculations indicate an average value of Q equal to 1.88. This finding shows that the majority of mass loss can be attributed to pyrolysis. The fact that the extent of reaction varies only slightly over the range of test conditions has been examined in the context of the two component hypothesis of coal constitution. This approach leads to the conclusion that the reaction of the "easily evolved" component VMI is extremely rapid and that the majority of it is removed from the coal in times less than the residence time in the system. This means that the volatile residue remaining in the char can be considered to consist of component II, VMII. If the mass fraction of VMI = 0, then an activation energy of 18.0 kcal is obtained for the pyrolysis reaction. If the mass fraction is assumed to be 0.75, the activation energy increases to 31.2 kcal.

Jan 1, 1978

The San Manuel district of Arizona was first prospected prior to the Civil War, but there was little or no production until 1881. Small operators tried to develop ore bodies from time to time after that without success. Then, in 1917, a drilling program was carried out; but it did not indicate a copper content of interest. Finally, in the 1940s, the U. S. Geological Survey drilled the property and obtained indications of a mineralized area. At that time, Magma Copper and its principal owner, Newrnont Mining Corporation, drilled many deep holes through the gravels and conglomerates and in 1948 proved an ore reserve of 367 million tons of 0.785% copper sulfide ore. Underground exploration and development were started in early 1948, and in 1953 design and construction of the surface facilities commenced. By the end of 1955 plant construction was completed. The ore deposit of disseminated pyrite, chalcopyrite, chalcocite, molybdenite, silver, and gold is in quartz monzonite porphyry gangue. Mine production, which is entirely underground, is by full-gravity block-caving. Initially, ore mined at a rate of 36,000 tpd was hoisted through two identical shafts. From the 5,000 ton coarse ore bins located at the collar of each shaft, the ore was hauled by a shuttle service rail- road in 100-ton bottom-dump rail cars a distance of seven miles to the rail bin. Fragmentation from block-caving supplemented by underground grizzlies at the loading stations controlled the oversize material to give a feed size acceptable to the two 7 ft standard Syrnons crushers. During operation, however, it became evident that a large amount of secondary breaking in the grizzlies was necessary to produce a suitable feed for the standard crushers. The decision was then made to install primary gyratory crushers on the surface adjacent to the shaft site ore bins. Under each 5,000-ton coarse ore bin, an 8ft by 20 ft (2.44 m by 6. 1 m) apron feeder transfers the ore to a 13 ft 6 in. by 10 ft (4. 1 m by 3. 05 m) grizzly set at 6 in. (152 mm) and sloped at 45 degrees. About 65% of the ore passes the grizzly and thus bypasses the 42 in. by 65 in. (1.07 m by 1. 65 m) Allis -Chalmers gyratory equipped with a Hydroset mechanism and having an open side setting of 5 ½ in. (140 mm). Grizzly undersize and crushed ore drop onto a 6 ft by 30 ft (1. 83 m by 9. 14 m) variable- speed apron feeder for transfer to a 54 in. by 90 ft 5 in. (1.37 m by 27.6 m) inclined conveyor equipped with a tramp iron detector. Indication of tramp iron automatically stops the conveyor and both apron feeders. When the iron is removed from the belt by the operator,

Jan 1, 1978

By G. R. Guillet

THE LATE Dr. D. F. Hewitt, Ontario's foremost authority on industrial minerals, was the first to point out the importance of urban minerals when he produced figures (Hewitt 1968) to prove that the Toronto-Hamilton area was Ontario's second largest mining camp in 1966 (Fig . 1). In that year, the value of mineral production within a 60-mile radius of downtown Toronto exceeded individually that of Steep Rock, Kirkland Lake, Timmins, Manitouwadge and Elliott Lake. Only the nickel and precious-metal production of Sudbury .surpassed in value that of Toronto's pits and quarries. Although that position was unchanged for some years during the early sixties, it was admittedly an unusual situation: gold was still pegged at an artificially low value; uranium was stagnant; and Texasgulf had not entered the scene. However, the point had dramatically been made. The combined value of production from hundreds of sand and gravel pits and dozens of limestone and shale quarries was of formidable proportions. The mining industry of the urban fringe could not be denied. Construction aggregates, cement, building stone and bricks were fueling an apparently insatiable appetite for urban expansion and redevelopment.

Jan 1, 1978

INTRODUCTION This chapter summarizes porphyry copper deposits within the State of Alaska. Prospecting for porphyry copper-type deposits in Alaska germinated during the 1940's, grew slowly during the '50's, boomed during the '60's, and matured in the '70's. Although large expenditures have been made in the search for porphyry-type deposits, most accrued data lies dormant in company files. However, an adequate base exists in the literature for a general synthesis of areas that contain porphyry prospects. To simplify the summary, porphyry molybdenum deposits as defined by Clark (1972) are omitted. Description of deposits in their geologic setting permits some correlations between deposit characteristics and crustal environment. These correlations allow speculation about the genesis of the deposits. The summary also attempts to group deposits on the basis of general mineralogic characteristics because diorite model deposits are separated from quartz phenocryst-bearing hosts. Data presented in this chapter summarize observations by the author, published descriptions of specific areas and deposits as noted in the bibliography, and comments by various government geologists. E. M. MacKevett, Jr., D. H. Richter, and H. C. Berg of the US Geological Survey have been particularly helpful. Because few comprehensive descriptions of individual porphyry copper deposits exist for this area, much of the data presented is new to the literature. Details of structure, isotopic geochemistry, and petro- genesis for individual deposits are largely lacking and even the general geology of some belts is not well understood. Details on petrography of Alaskan porphyry copper occurrences are inadequate for construction of ternary diagrams (e.g., Figs. 36a, b, pp. 103, 104, for the northern Cordilleran orogen). Petrographic descriptions summarized in the text are largely from published descriptions whose sources are cited. Porphyry copper-type deposits in Alaska include deposits with pervasive pyrite that contain disseminated copper (but not necessarily coproduct molybdenum). Available data preclude differentiating the deposits by size. No Alaskan porphyry copper deposit is now in production but this is believed to be, in part, a function of economics. In some cases available geologic information is in- adequate for classifying deposits. Some de- posits included with porphyry copper may, with further exploration, be demonstrated to be some other genetic type. Alaska has three distinct porphyry copper provinces: the Hogatza plutonic belt, the Continental Margin belt, and the Interior belt. Each belt contains deposits with characteristic geologic features distinct from those of other belts. Fig. 24 shows the continental margin belt to extend inland from

Jan 1, 1978

By Peter F. Steidl

Seven degasification wells have been completed in the Pittsburgh coalbed at the new Emerald mine near Waynesburg, Pa. Funding was provided by the Bureau of Mines to perform stimulation treatments on five of the wells, to show that this is a feasible and economical means of degasifying part of a coalbed. The seven wells ranged in depth from 590 to 910 feet. Stimulation treatments used 25,260 to 42,660 gallons of foam and 7,400 to 12,800 pounds of 20/40-mesh prop sand. Pumping rates were 10.8 to 11.6 bbl/min and treating pressures were from 1,050 to 1,600 psig. On the day following stimulation, gas production ranged from a few hundred cubic feet per day to more than 100,000 cu ft/day.

Jan 1, 1978

Electric power curtailments resulting from the coal strike, required Noranda Aluminum, Inc. to shut down its 140,000 ton-per-year (tpy) primary aluminum smelter at New Madrid, Mo., and layoff 308 workers. Other primary aluminum production facilities affected by the coal strike included the Aluminum Company of America plant at Evansville, Ind. which shut down half of one potline; the Eastalco Aluminum Co., smelter at Frederick, Md., which cut production by 7 percent; and the National-Southwire Aluminum Co. plant at Hawesville, Ky. which cut production by 6 percent. Alumax, Inc. announced that construction had started on a 91,000 tpy potline at the Eastalco primary aluminum smelter. The new potline will be owned 65 percent by Alumax and 35 percent by Mitsui & Co. Ltd. Howmet Aluminum Corp., which currently owns 50 percent of the existing 176,000 tpy facility, has the option of becoming a 50 percent owner of the third potline in 1982. Construction of the new line was scheduled to be completed in 1980.

Jan 1, 1978

By J. Kitagawa

The principal objectives of a metallurgical test programme for a 'grass roots' mining project are twofold. The first requirement is to establish the metallurgical viability of the project by demonstrating that acceptable results can be obtained by processing of the ore. The second goal is to obtain essential supporting data to determine whether the project is economically feasible. This involves several functions, which include the establishment of a workable flowsheet, the obtaining of design criteria for the commercial plant, and the collection of the evidence necessary to convince management, and often a third-party expert, that the metallurgy predicted for the ore can be achieved in a full-scale operation. The latter task is facilitated if a coherent overall picture is presented considering the geology of the orebody, the mining plan, and the mineralogy and metallurgy of the ore. The purpose of this paper is to provide guidance in the establishment of a test programme to meet the above objectives.

Jan 1, 1978

By Richard A. Grieve

A 63.5 metric tons per hour (70 TPH) demonstration coal preparation plant was constructed on the Iowa State University campus, Ames, Iowa, as a part of the Iowa Coal Project funded by the state of Iowa and administered through the Energy and Minerals Resources Re-search Institute. Processing equipment in the plant circuit includes a heavy media separator, concentration tables, separating and dewatering screens, and conveying equipment. Coal samples of size 907 metric tons (1000 tons) with sulfur contents ranging from 2.5 to 8.75% sulfur from seven mines in the state of Iowa have been pro-cessed in the plant. Sulfur reductions have averaged 35%. With ash reduction averaging 45%. Equipment for advanced fine coal beneficiation research is currently being installed in the plant to include a slurry pretreatment circuit, froth flotation, oil agglomeration, pelletization, hydrocyclones, advanced design thickener and disc filtration.

Jan 1, 1978

By Alan E. Bland, Jerry G. Rose, Thomas L. Robl

This paper describes the observed variability of the chemical composition of coal preparation plant refuse for the major producing seams of Kentucky. Both the Appalachian Coal Field of eastern Kentucky and the Eastern Interior Coal Field of western Kentucky are represented. Also reported is the variability observed in the chemistry of the coal refuse due to cleaning, and the observed chemical variations between past and present production samples. This represents part of a larger study directed toward characterization and utilization of Kentucky coal refuse.

Jan 1, 1978

By Alden B. Carpenter

Brines (a solution containing more than 100,000 mg/l dissolved solids) in sedimentary basins are genetically related to evaporites in one of three ways: (1) dissolution of evaporite minerals, generally halite; (2) interstitial fluids in evaporites which are expelled from their source rock during compaction; (3) incongruent alteration of hydrous evaporite minerals (carnallite). Most brines of commercial interest originate as interstitial fluids in halite-rich rocks. These fluids are initially rich in magnesium, sulfate, and potassium but evolve in composition to an Na-Ca-Cl brine during their migration to their present host rock. A particularly important reaction in this process is: 2CaCO3 + Mgt+ = CaMg(CO3)2 + Cat (1a) This reaction reduces the magnesium content of the brine and ultimately converts it to a calcium-rich brine. The loss of sulfate occurs by two mechanisms. One of these is by direct precipitation as calcium sulfate (either as gypsum or anhydrite): Ca 2+ + SO4 2- = CaSO4 (2a) Additional sulfate may be lost from the brine by sulfate reduction: S042 + 1.33CH2 + 214- = H2S + 1.33CO2 + 1.33H20 (3a) The loss of carbonate species occurs by precipitation as carbonates: H2O + C02 + Cat = CaCO3 + 2H+ (4a) The net result of reactions 3 and 4 is: Ca 2+ + SO4 2- + 1.33CH2 = H2S + CaCO3 + 0.33H2O + 0.33CO2 (5a) The loss of potassium from brines is caused by the formation of potassium aluminosilicates: 2K+ + Al2Si2O5 (OH)4 + 4SiO2 = 2H + 2KAlSi2O8 + H2O (6a) The hydrogen ions produced by this reaction dissolve carbonates: 2H+ + CaCO3 = Ca 2+ + CO2 + H2O (7a) The net result of reactions 6 and 7 is: 2K+ + CaCO3 + Al2Si205 OH)4 + 4SiO2 = Ca2 + 2KA1Si3O8 + H2O + C02 (8a) A study of brines from central Mississippi has shown that the composition of these brines is related to the interaction of pore fluids from evaporites with minerals in the enclosing sedimentary rocks.

Jan 1, 1978

By Gunnar Thaning

The iron ores mined by LKAB in the north of Sweden have excellent beneficiation properties. This gives LKAB a favourable position as regards the production of low silica pellets for direct reduction. LKAB have concentrated on developing and marketing grades of pellets for the Midrex-Purofer-HyL process group, i.e. such D.R. processes which are carried out in a shaft furnace or a static bed using reformed natural gas as a reducing agent. The paper deals with properties and quality demands of iron ore pellets for such processes. Matters such as the effect of the residual magnetite in the fired pellets on the degree of metallization, the amount and composition of the slag phase in the pellets, the mechanism of the disintegration during reduction, the state of swelling of the pellets during the conditions prevailing in these processes, the importance of the porosity, the improvement of the reducibility and lowering of the sticking tendency of the pellets by small additions of suitable additives and the influence of the pellet size are discussed. A special test procedure for D.R. pellets has been elaborated by LKAB. Thus, three metallurgical properties are routinely determined separately, namely reducibility, reduction strength and sticking. The test methods are described. Finally the present and future LKAB pellets for direct reduction are presented with respect to chemical analyses and metallurgical properties.

Jan 1, 1978

By Jack E. Fraley

The Bureau of Mines has successfully developed and tested a machine for spraying sealant onto coal mine roof and ribs. Dry material is transported pneumatically to a water-adding nozzle designed to provide dust-free spraying while being nonplugging and self-cleaning. The machine is self-cleaning, 35 inches in height, and capable of applying l/2-inch-thick coatings at over 1,000 ft2/hr.

Jan 1, 1978

By M. J. Slater

Ion exchange using resins is one of the few processes capable of reducing ionic contaminants in effluents to very low levels. Continuous fluidized-bed ion exchange is an advantageous technique for processing dirty effluents and thin slurries. It also reduces resin inventory and equipment cost compared to fixed packed beds. A simple continuous fluidized-bed unit has been investigated for treating effluents and its performance is described. Breakthrough curves were first obtained from static fluidized fixed beds; these data were then used to determine the required operating conditions for a periodic-flow, countercurrent fluidized-bed ion exchange system. A waste stream, containing about 56 ppm copper, was treated in the continuous system using an extraction fluidized bed depth of 203 cm and a flow rate of 1.22 cm3/ cm2s (900 gph / sq.ft) to yield an effluent containing less than 0.02 ppm copper. A generalized design method is proposed for similar chemical systems.

Jan 1, 1978

By William P. Dyrenforth

The principle of electrostatic separation is discussed and elaborated on by dividing into the three main mechanisms of electrification as applied to separation of solid substances, i.e., (1) contact electrification, (2) electrification by conductive induction, (3) electrification by ion bombardment. Types of equipment used for electrostatic processing are described and the effects of humidity mentioned. Processing of iron ore, titanium minerals, rare earths and cassiterite is discussed and some existing plants are described.

Jan 1, 1978

By Thomas E. Shufflebarger

Glass sand is a virtually pure, fine- to medium-grained, quartz sand. It is produced in 25 states from a variety of chemically different source rocks. Deriving their raw material largely from either friable sandstones or loosely consolidated sands, 59 operations produced 14.9 million tons of melting sand in 1976. About one-third of this tonnage was obtained from the Oriskany and St. Peter Sandstones. Glass-sand prospects are discussed in this paper with regard to chemistry, environment, transportation, and costs. Demand for a quality product will range from 36 million to 46 million short tons in 1995.

Jan 1, 1978

By Peter P. Harvey

The Nonel Primadet is a non-electric delay blasting cap initiation system. The most recent field application of the system in the Southwest has been at the Magma Superior Mine, Superior, Arizona.

Jan 1, 1978

By William C. Grady

Microscopic pyrites are present in all West Virginia coals. Sizes of these pyrites range from 0.1 µ 500 µ (1/2 mm) , and four types are noted: massive, patches, framboids, and isolated crystals. The relative and absolute abundances of the four types vary from seam to seam, and these distributions have a marked effect on the ease with which a seam may be cleaned of pyritic sulfur.

Jan 1, 1978