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By J. A. Cox, R. S. Mattson

"One of the main problems encountered in employing sublevel caving is the inherent high dilution factor. The operating results at Granduc illustrate that this dilution can be closely controlled and satisfactory recoveries achieved, in base metal ores grading less than 2.0% copper equivalent, by using an assay grade control system based on the fundamental draw characteristics. The history of draw control procedures employed since the start of operations provides an effective comparison between this system and one based mainly on tonnage. The transverse and longitudinal sublevel caving mining methods are described and it is shown how improvements in design layout, operating practice and draw control in narrow complex ore zones (12-foot minimum width) have raised the operating performance of the longitudinal system to a satisfactory level."

Jan 1, 1973

By William G. Kegel

Aside from having a usable product and good mining conditions, the greatest asset for a profitable coal mining organization is an effective mine maintenance program. The first step in acquiring this is the presence of good mechanics-men who have a desire to be mechanics and who want to know more about the design and control of the machines in their charge. The knowledge and ability to be found in a good mechanic is the result of ambition, curiosity, and determination. With these qualities as a start, the aspiring mechanic can launch his career if he begins learning all he can about mechanics, electricity, and hydraulics. The path is rough, but the goal is rewarding. Mining machinery probably absorbs as much or more abuse than any other heavy equipment in use today. And when one considers the conditions under which much of the repair work must be done, it can be seen that the mine operator needs the best of men and tools to perform the service. MOTORS AND POWER SUPPLY Mining machines, from their inception, have utilized the electric motor; and down through the years of mechanization, this power source has undergone many changes to better adapt it to the job. The first motors used were large, heavy-framed, open d-c motors (direct current), using a series or shunt winding. A motor having one or more field coils connected in series and themselves in series with the armature, is called a series motor (Fig. 1). The series motor had the advantage of quickly developing starting torque, and it was, and still is, the best motor for locomotive or shuttle car tramming service. The series motor, however, speeds up as the load is reduced and, if not properly controlled, can overspeed. The shunt motor, as its name implies, has one or more field coils in

Jan 1, 1973

By R. M. Jacobs

Can your company afford to issue a check today for $100,000, $500,000, $2,000,000, or $22,000,000? This is what it might cost your company if it is on the losing end of a product liability suit. During the past 10 to 15 years, the number of product liability actions has grown from a handful per year level to a hundreds of thousands per year level. Settlements and awards in the tens and hundreds of thousands of dollars are not unusual in these days. The largest award that the authors haw heard about is a case involving a private airplane and the death of four men, which was awarded over $22,000,000. In the materials handling field, a fork lift truck, ordered with an overhead guard, was delivered without a guard because one was not available at the time. An accident with serious personal injury followed. Wouldn't it have been better to have waited until the guard was available before delivering the unit? Answer: a quarter of a million dollars better -- the cost of the settlement. Hoisting devices are also not without their liability precedents. In a 1960 case, an employee was injured when a load abruptly fell from a hoist. It was determined that the operator could not possibly have caused such a fall had the hoist been functioning properly. The case was compounded when the manufacturer of the hoist contended that the load had been improperly connected to the device, since the same hoist was used to remove the weight from the injured man without another malfunction.

Jan 1, 1973

By E. Howard Lambert

"Operating costs of mining plants are increasing due to the increased cost of labour, materials and fuels. Labour and materials costs are factors not readily controlled. However, the use of energy from fuels may be controlled by plant operations. This paper describes the fossil fuels, their expected rate of depletion and their costs. The paper considers methods which may be used to provide an efficient use of energy from fuels. It includes an outline of obtaining energy, as heat, from mine milling operations (air compression) and obtaining the maximum use of energy from fuels used to generate electricity."

Jan 1, 1973

By I. J. Lin

The effect of various types of structural modification on the critical micelle concentrations (CMC) and hydrophile lipophile balances (HLB) of certain surfactants has been considered. Using the concept of effective chain length for the substituted species, an index of hydrophobicity (I) has been defined. It is hoped that such an index will allow one to choose surfactants for particular purposes in a less arbitrary fashion than heretofore.

Jan 1, 1973

By S. S. Sephton

Sintering as applied to agglomeration of ferrous fines has shown little growth in the United States in recent years. The general concensus was that most of the existing facilities would remain in production at a reduced tonnage to dispose of and recover solid waste from steel plants. Further growth for ferrous sintering technology was not in sight in the United States and in the early sixties expansion came to a virtual standstill, however, we witnessed a rapid emergence of a tremendous pelletizing industry. On other continents, due to different raw materials supply and capital structure, sintering technology continued to grow, with a more cautious development of pelletizing installations. In the U.S. the diminishing supply of good quality, high grade coarse ore resulted in eventual disappearance of high grade ore fines for sintering. The finely divided concentrates produced from lower grade ores were not amenable to this type of agglomeration, but were more suitable for pelletizing. Furthermore, pellets seemed to possess all the features of an ideal blast furnace feed; namely pellets are free flowing, uniform in size, strong, with extremely uniform chemical composition and good reducibility. Importance and demand for such well stabilized furnace feed further increased as size of newly installed blast furnaces continued to grow. The in- creasing demand for a uniform, stabilized burden coincided with the effort to produce a fully beneficiated burden for smelting, thus reverting the blast furnace to its primary function of smelting.

Jan 1, 1973

By J. G. Speight

Laboratory studies indicate that autogenous heating of low-rank coal can be prevented by a prior treatment which involves immersing the coal for short (5-15 min.) periods in an inert liquid at temperatures between ~ 350° and 400°C. Such "carbonization" effectively reduces the accessible pore volume of the coal to levels at which heat generation through subsequent sorption of moisture and oxygen is too slow to cause significant temperature rises in a stockpile. In addition, this treatment also irreversibly removes most of the moisture held in the raw coal and raises its calorific value by as much as 10-12%.

Jan 1, 1973

By H. A. Hamza, J. Visman

"This is a report on the combined application of ""long-chain"" flocculants and classifier cyclones in the field of slimes treatment, with emphasis on the simultaneous thickening and clarifying of industrial effluents, at low cost. The principle of the process described below involves: (1) the formation of small floes of relatively great strength, by sequential dispersion and conditioning, with average floe size of about 1501 microns; (2) the floes being of sufficient strength to withstand the shearing forces operating within a cyclone and consequently behaving as solid particles with an equivalent diameter (Stokes) that exceeds the size cutpoint of the classifier cyclone; (3) the removal of flocculated solids by means of a classifier cyclone the size cutpoint of which permits effective separation of these solids from the water. Results of test work to date indicate that a broader use of cyclones in industry is possible with the above types of flocculants because the submicron particles and colloidal material are readily collected and clear water is produced, with the attendant advantages of compact construction and low cost that are characteristic of centrifugal separation. The process generally permits classifier cyclones of medium throughput capacity (e.g. 12-in. diam.) to be used for clarifying effluents that contain minus 10-micron particles."

Jan 1, 1973

By K. N. Subramanian, H. Kanduth

"It is well known that chalcopyrite can be dissociated into simple sulphides by heating with elemental sulphur at about 475°C:CuFeS2 + S -> CuS + FeS2Experimental work was undertaken to determine whether this ""activation"" could be used to advantage in the selective leaching of copper from chalcopyrite concentrate.A method of treating copper concentrate with molten sulphur was developed and the activated product was leached in dilute sulphuric acid using oxygen, ferric iron or manganese dioxide as the oxidant. The object was to obtain a solution suitable for electrowinning with minimal purification, but it was impossible to obtain rapid extraction of copper without simultaneously dissolving a large proportion of iron. This was attributed to the fact that some of the copper was present as a low iron-copper sulphide (idaite) and that the pyrite formed during the ""activation"" step was more easily oxidized than natural pyrite."

Jan 1, 1973

By Christopher Haycocks

The growth of computer and ground control technology in recent years, combined with an urgent demand for low-cost fossil fuels and mineral resources, has set the stage for full-scale utilization of computers in mine planning. Steeply rising production costs and the need to preserve the environment are placing great demands on engineers to improve their mining efficiencies, which can best be accomplished by applying the full capabilities of the computer. Pressure to develop and perfect programs with an immediate potential for improving mine de- sign, reducing mining costs and extending the viable coal reserves of the country has already come to bear in the form of exploding energy requirements, environ- mental considerations and the visible limitations of other energy sources. The computer program discussed in this paper, RAMPLAN (Rock Mechanics Applied to Nine Planning), was constructed as part of a continuing effort at Virginia Polytechnic Institute & State University under the sponsorship of the Office of Coal Research to develop a suite of programs to benefit the mining engineer in improving mine design and evaluation techniques. This program averages out structural data values obtained from randomly placed or gridded point sources across a mining property and uses these values in structural design equations. The basic purpose of the program is to provide accurate estimates of mineable tonnages, based on a realistic assessment of structural conditions existing in the deposit, for use in subsequent evaluation programs. Program output, however, also provides sound engineering data for the mine planner to use in planning and laying out new properties. Mining dimensions produced by the program provide a good starting point for initial layouts; and as more refined procedures are developed for increasing and improving the quality and quantity of information from boreholes, this information may be used with increasing confidence. The rock mechanics principles utilized in the program are generally well-established with full details provided to the user. To produce meaningful results extensive input data, obtained from exploration borehole core data, outcrop sampling points, or mine samples, are required. To assist the engineer, details of the types of tests that should be conducted have been listed. By including all of the ground control equations in the program the otherwise long and tedious calculations can be performed easily and quickly, and the work can provide the basis for a more detailed ground control study. The program is written in Fortran IV Level G to run on an IBM 3701155 ASP and requires 156K storage.

Jan 1, 1973

By G. C. Kachel

Significant effort has been expended and considerable success has been realized m the application of instrumentation and automatic control equipment in the mining and ore processing industries. This effort has been applied principally to process equipment with the objective of increasing throughput, minimizing labor requirements and/or improving grade or product quality. Less spectacular, but quite rewarding has been the successful application of instrumentation and automatic control equipment to a wide variety of material handling equipments. This paper describes some of this work including: (1) automatic weighment of load-haul-dump units and trams underground; (2) automation of skip loading; (3) instrumentation applied in feeders and conveyors; (4) level measurement in bins, silos, vessels and sumps; (5) automatic blending of sized materials; (6) automatic loading of ships, trains and trucks; (7) automatic control of tailings disposal facilities

Jan 1, 1973

By Saul Escalara

Data on sulfonate adsorption by silicate minerals are very scarce in the literatures. Perhaps the only comprehensive paper written on the topic was done by Fuerstenau and Bhappu (1); this work dealt exclusively with quartz but included many important suggestions as to the form and nature of the hydroxy-sulfonate species of some cations formed during the conditioning step and their effect on the flotation response of quartz. Another paper by the same authors (2) contains additional data on the role of hydrolysis in sulfonate flotation of beryl. As postulated by Fuerstenau and Bhappu, a solid form of cationic sulfonate functions as the collecting species to produce flotation of quartz and beryl. According to the authors, the solid compound is a hydroxy-sulfonate of a given cation, where the hydrogen of the hydroxyl part provides a means for bonding of the species to the mineral surface; thus, the presence of hydroxyl in the neutral precipitated compound is of primary importance to produce flotation. Although the preceding examples illustrate the effect of a sulfonate collector in silicate systems other than plagioclases, they are important as examples of processes of hydroxy-sulfonate complex formation. Since the plagioclase minerals con¬tain Ca(II) and Al(III) cations, which are very reactive in sulfonate media (1), the formation of hydroxy-sulfonate compounds with these cations released from the solid phase may well prove to be the cause for their flotation.

Jan 1, 1973

By W. Chi, R. Regan, R. A. Washington

"In uranium mines, the purification of underground mine air can be accomplished by the removal of dust particles and radon daughters using filters. Full-scale statistically designed experiments with flow rates up to 10,000 cfm have been conducted at Denison Mines Ltd. on mine air filtration with vermiculite as a filter material. Various filtration bed thicknesses were chosen, with different face velocities through each bed thickness. Results on total dust, respirable dust and radon daughter collection efficiencies were analysed statistically. It is shown that these collection efficiencies are directly related to the filter bed thickness. However, the different face velocities seem to affect only the collection of radon daughters. Optimum collection efficiencies for a clean bed of about 30% were found for respirable dust and radon daughters, and about 41>% for total dust, using an 8-in.-thick bed and a face velocity of 500 fpm. Dust build-up on the filter bed during operation led to an increase in collection efficiency, reaching 40 to 60% after two weeks."

Jan 1, 1973

By J. D. Grenia

The Buick Mine is a joint venture of American Metals Climax, Inc., and Homestake Mining Company located 120 miles by road southwest of St. Louis, near the village of Boss, in the 'New Missouri Lead Belt' (See Figure 1). Since start-up in 1969, over four million tons of lead-zinc ore have been mined and milled at Buick. Situated about 1,100 feet below the surface at an elevation 270 feet above sea level, the flat lying sinuous ore bodies are up to 250 feet wide, 85 feet high and several thousand feet long. Mineralization is galena, sphalerite and chalcopyrite in dolomite, Access to the mine is through two 18'Ø concrete lined vertical shafts - one for servicing and the other for hoisting ore (See Figure 2). The mine is being worked by a modified room and pillar method using both rubber tired equipment and a sub-level rail haulage. Ore is broken from first pass headings, back and bench faces and transported by load-haul-dump units to ore passes located on 900 foot centers. The ore is pulled from chutes on the sublevel 90 feet below into 15 ton bottom dump cars and delivered in 10 car lots by a 15 ton diesel locomotive to a 42" gyratory crusher (See Figure 3). A recent innovation has been the introduction of two 50 ton trucks with plans to haul up to 60% of the ore on the mining level to an ore pass feeding directly to the primary crusher (See Figure 4). Ventilation raises up to 16'Ø, which were originally planned for 900 foot centers, are now driven on 450 foot centers.

Jan 1, 1973

By W. B. Morrey

This paper deals with the development of the new cap-sensitive slurry explosives. The history and special features of these explosives are outlined, and recent field trials are described.

Jan 1, 1973

By K. Duckworth

The treatment of Turam data by conventional procedures does not permit the interpreter to make any estimate of induced current magnitudes. This problem may be overcome by using an alternative data treatment procedure. It is shown that the conventional and alternative procedures are equally satisfactory in terms of their ability to provide the location of line currents and estimates of conductor quality. A full description and evaluation of both procedures is presented in conjunction with field examples to show how the alternative procedure may assist interpretation when used to complement the conventional approach.

Jan 1, 1973

By L. W. Saperstein

Surface mining of coal is undoubtedly one of the more controversial aspects of the mineral industries today. There is a constant tug between the need for readily available and inexpensive energy supplies and the desire to minimize disturbance to the land. Without a doubt, surface mining severely disturbs the land surface. The duration of this disturbance, from a minimum of a few months to a maximum of infinity, however, is strictly dependent upon the mine operator's willingness to reclaim. Surface mining critics claim that it is impossible to ameliorate the detrimental effects of this mining to insignificance. The more vocal critics, indeed, are calling for complete abolition of surface mining for coal. Thus, they do not believe that it is possible to restore surface- mined land to pre-mining conditions. As a consequence of this position, an adversary relationship has developed between the operators and their critics who, simultaneously, believe they are doing their best for the United States. In a forum of mining experts, there is little need to recount the kind and amount of devastation that can result from poorly reclaimed land. This has been done numerous times, including once 1 by the author. Of particular interest to this paper, though, are the environmental hazards associated with contour strip mining. In addition to the problems of area mining: denudation of vegetation; exposure of toxic spoil; increase of erosion runoff; etc.--contour mining has the very real problem of landslide due to the outslope stacking of overburden. Contour mining is understood to be the extraction of coal from a hillside outcrop such that the resultant pit follows, or nearly follows, an elevation contour. The problem with contour mining as usually practiced is that the spoil from the cut, or the first cut if multiple cuts are made, is placed on the outslope. If this slope is steep, the resulting pile is difficult to stabilize, generally erodes swiftly, and may fail disastrously.

Jan 1, 1973

By Robert Louis Adams

A general discussion of the structure of the junk automobile recycling system shows that the generation of stripped automobile hulks and scrapped automobiles is price inelastic. As a result, it is extremely difficult for the price mechanism to automatically achieve an equilibrium that will prevent the accumulation of excessive automobile wrecker inventories and vehicle abandonment by the last owners of scrapped cars. The new shredder processing technology and the new portable flattener technology have altered the structure of the junk automobile recycling system. The shredder technology has increased the demand for processed automobile scrap. This increased demand is reflected in higher prices paid for hulks by scrap processors. The portable flattener has reduced the transportation cost of shipping hulks to processors. The two new technologies have eliminated, at least potentially, the net cost of shipping stripped hulks so frequently incurred by wreckers in the past. The elimination of this cost eliminates the economic incentive for excessive wrecker inventories. Unfortunately, the incentive for last owners to abandon their cars does not appear to have been eliminated by the new technologies. The last owner of an automobile with no spare parts value is still likely to incur a cost by delivering his automobile to the recycling system. Although a subsidy payment is probably unnecessary to reduce excessive wrecker inventories, such a payment might be one solution to the problem of automobile abandonment. However, there are a wide variety of subsidy programs that could be introduced. Before any Federal subsidy program is introduced to reduce automobile abandonment, it is recommended that the program be tested on a limited basis in many different parts of the country.

Jan 1, 1973

By Howard J. Pincus

The purpose of the study is to investigate the effects of fracture filling and associated alteration on the mechanical behavior of rocks. Results are presented for specimens from the Climax and Henderson mines in Colorado and the San Manuel mine in Arizona. The rock types studied from each location are from 1) Climax, medium-grained - granite, fine-grained granite, granite porphyry, schist, and gneiss; 2. Henderson, rhyolite porphyry; 3. San Manuel, quartz monzonite and quartz monzonite porphyry. A description of the rocks was made including: color, texture, mineral composition, composition and fabric of fracture fillings, density and porosity. Unconfined and triaxial compression tests were run on the Climax and San Manuel specimens. Sonic relocities were measured during the compression tests; Shore sceleroscope hardness was measured before the compression tests. Tentative conclusions are that some relation appears to exist between compressive strength and the following properties and features for all the specimens: dynamic Young's modulus, sonic velocity, density, rock composition, and composition and fabric of fracture fillings - veinlets. There appears to be some relation between compressive strength and Shore scleroscope hardness and porosity for quartz monzonite (San Manuel). A relation appears to exist between compressive strength and texture for schist and between com¬pressive strength and extent of failure on fracture fillings for fine-grained granite, schist, and gneiss (Climax). We plan to perform additional analyses of data collected so far and data yet to be collected in the next few months, with emphasis placed on devising a practical index of alter¬ation that can be used in the field. Limitations on interpretations arise from such factors as heterogeneity of the rocks studied, the small range of confining pressures used, and other factors presented in the text.

Jan 1, 1973

By Bill Linville

During calendar year 1972, the Bureau of Mines was engaged in some 20 major areas of research for the development of new and improved efficient methods of conservation and utilization for petroleum and natural gas, oil shale, and coal. Made up of numerous projects described in this report, the program was carried out through research performed at research centers and laboratories in the field supervised and supported by administrative personnel of this Bureau of the Department of the Interior. Based un this research, 186 technical reports were published by the Bureau or others, and numerous other reports were prepared for Federal agencies, State agencies, and organizations engaged in cooperative research programs with the Bureau.

Jan 1, 1973