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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

The mineralogy of ten trihydrate bauxites and their leached residues from bomb digestion tests at 140, 180 and 2400C was investigated and the resultsòcorrelated with analytical data. It is shown that increased recovery of alumina at high temperatures is due to. the dehydroxylation of goethiteòrather than the presence of alumina monohydrates. The effects of aluminous goethite -on the interpretation of "available alumina". results-and normative analysis are discussed and it is concluded that,'cautionòmust be exercised in interpreting the results of bomb digestion tests in terms of alumina hvdrates.

Jan 1, 1973

By J. R. Maxwell

Large capacity flotation cells with volumes ranging in size from 300 to 2000 cu ft are used in the Opemiska concentrator, Opemiska Copper Mines (Quebec), Canada. This paper gives a description of the flowsheet with metallurgical comparisons using Maxwell vs. conventional cells, total power consumption used, and estimated maintenance costs.

Jan 1, 1973

By Fred J. Fleischauer

Industry requires higher speed sheet stacking. High speed sheet stacking requires equipment and techniques to solve several inherent difficult problems, such as the tendency for sheets to sail, and the need for a means to absorb the kinetic energy of the sheet without damaging the sheet. Accurate alignment of the sheets on the stack is another problem difficult to solve. The paper first analyzes the process of sheet handling into its basic elemental steps. It then describes equipment and techniques presently used for moderate sheet handling speeds, with emphasis on how each step in the stacking process is accomplished by the present equipment. The limitations to speed-up of present equipment is discussed. New high speed equipment, either recently introduced to the market, or in the process of development, is described. Magnetic, air float and vacuum conveyor stackers are compared.

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 Richard L. Stowe

Four NX-diameter holes were diamond-drilled in competent granite. Samples of the recovered core were used in laboratory tests. A borehole, plate-bearing device known as a Goodman jack was used to perform load deformation tests on the rock in the core hole. The majority of samples used in the laboratory tests were taken from depths in the hole at or within 5 ft of those at which the plate bearing tests were made. Borehole camera records, compressional and shear wave velocities, and densities were measured. Dynamic elastic constants were computed for the in-situ material, while comparative data (except camera records) were obtained in the laboratory. These data were examined to evaluate the significance of the in-situ modulus of deformation (Ed), the value computed from Goodman jack tests. Average test results show an excellent correlation between in-situ and laboratory data. The ratio of laboratory to field deformation modulus ranges from 9.82 to 7.21 for 3,000 and 9,000-psi stress levels, respectively. The dynamic modulus ratio, ED field/Ep lab, is 1.02; the compressional wave velocity ratio, V8 field/V8 lab, is 0.94; the shear wave velocity ratio, V, field/V, lab, is 1.12; and the density ratio, field [y/y] lab, is 0.95.

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 Wescomb R. Jones

The United States is the world's largest producer of hydrofluoric acid (HF), with its 1971 output of 317,000 short tons representing about 40 percent of the estimated Free World production. U. S. production has increased over five fold in the past 20 years, with a growth rate of about 7 percent per year between 1960 and 1970. However, the growth rate to 1977 is expected to be less than 5 percent per year, due primarily to a reduced rate of growth in requirements by the aluminum industry and an expected increase in imports from Canada and Mexico. This discussion will include our analyses of the consumption pattern for HF in 1972 and the factors influencing the demand forecast for 1977.

Jan 1, 1973

By W. T. Robertson

My charge is to review briefly "Coal In The Electric Utility Industry - Present and Future." Thus, I will not dwell on the overall energy picture, other than to express what most others involved in the energy picture know - we're in trouble! Several years ago, speaking to another engineering society, I said, "Much has been and yet will be said and written about the energy situation in our Country." What an understatement! The energy question has reached crisis proportions and is a top priority item at the highest level of government, Unfortunately, it will be in that situation for some time to come. Many factors created this complex problem, and we all share some of the blame. But I am perplexed when I read in the popular press that environmental factors are unrelated to the energy crisis when I know this to be untrue. In the recent past all forms of energy have been cast in the role of villain, particularly coal with its problems of surface mining, mine safety, acid water drainage, sulfur content, and a multitude of other adverse factors relating to the environment in one way or another. As you know, the sulfur situation has led to the closing of numerous mines, resulting in the lessening of our mining capacity. Today, along the Eastern Seaboard, 60 to 70 million tons of coal are displaced by imported oil, primarily to meet air standards. Even in the Midwest, utilities sitting on enormous coal reserves are converting to other fuels or hauling low sulfur coal thousands of miles from the western Mountain States. [We will hear more about this coal from another speaker on the program this morning.]

Jan 1, 1973

By G. Bjorling

The opening oxidation of a hydrometallurgical treatment of natural sulphides must for several reasons be so controlled that a maximum of the sulphide sulphur is transformed into elemental. If the oxidation is performed at low pressure and moderate temperatures and with mild reagents such as diluted nitric acid (or ferric or cupric chloride) the just mentioned condition is realized and it has been found possible to conduct the reaction so that solutions are obtained from which the metals can be recovered and the reagents required for the dissolution are regenerated. Experiments in laboratory scale with nitric-acid promoted oxidation have shown that this method is applicable to several types of raw materials, and in combination with electrodialysis both for partial neutralization and for final regeneration of the circulating acid can the requirements of low consumption of chemical reagents and formation of harmless residues be well fulfilled. The metals can be recovered as cathodic deposits or as hydroxides, and the method should be applicable also for low grade ores and concentrates. Although oxidation of sulphides by ferric or cupric ions has the advantage that it can be performed in open vessels it seems well worth the complication of working with nitric acid promotion in a low-pressure autoclave. Also complex sulphidic, oxidic and metallic materials can be treated.

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 V. N. Mackiw, D. E. Weir, D. J. I. Evans

The world's largest reserves of nickel are found in lateritic ores. Commercial exploitation has been carried out for almost one hundred years; however, none of the plants currently in operation produce pure nickel but rather ferronickel, matte, impure nickel oxide or mixed sulphide precipitate. Over the past decade Sherritt has studied various processes, including the modified reduction roast-ammonia-ammonium carbonate leach process, for the production of pure nickel powder and briquettes from laterites. Nickel can be reduced to the pure elemental form at elevated temperatures and pressures from impure basic nickel carbonate slurries. Several methods were studied in the development of the process for working up the pregnant leach liquor and basic nickel carbonate to produce feed for the aqueous hydrogen reduction step in which pure nickel powder is produced. This paper is concerned only with the laboratory studies using the basic nickel carbonate slurry reduction procedures.

Jan 1, 1973

By Arthur P. Nelson

In opening, I want to thank the program committee and members of the Society of Mining Engineers of AIME for the opportunity to speak to you. Various chapters of AIME this past year have expressed interest in the Federal Metal and Nonmetallic Mine Safety Act. We want to see that interest continue, because the reason for the legislation was the safety and health of the industry's workforce. The Department of the Interior was directed by the Congress to administer the provisions of the Act and is therefore held directly accountable for the success or failure of its intent. We intend to see it succeed. Among other things, the Act does provide for education and training under Section 15. This provision has been implemented and is expanding. However, the responsibility of my office is inspection and enforcement and that is my subject today.

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 R. H. Knudsen

"In view of the chronic overcapacity problem in the world potash industry and Saskatchewan's recent emergence as a major producer, the long-term outlook for potash productive capacity and consumption is of importance and interest to both the Saskatchewan Government and the potash industry. This paper is based on a report recently published by the Saskatchewan Department of Mineral Resources on projected world potash productive capacity and consumption for the ten-year period 1970 to 1980. Potash productive capacity and consumption are estimated on a country and regional basis and projected annually to 1980. Tables and graphs are included which summarize projected capacity and consumption for the period and illustrate the impact of Saskatchewan's capacity upon the North American and world potash industries."

Jan 1, 1973

By K. Thirumalai

The Bureau of Mines has developed and tested a new concept of combining thermal and hydraulic energy processes for hard rock cutting. The study shows that this novel combination method overcomes the fragmentation limitations of the thermal process in nonspalling rocks and the cuttability limitations of the hydraulic process in high-strength rocks. The method effectively cuts hard rocks at moderate hydraulic pressures (below 30,000 psi). Theoretical predictions of the rock damage process are made and are correlated with experimental results obtained by using both single pulse and continuous water jet hydraulic systems. Traversing point heating and line heating techniques were used for heating rocks preceding the continuous jet impingement. Heating induces structural weakness of the rock material and assists fragmentation by the water jet impingement. The thermohydraulic process is effective if the significant depth of heat penetration induced by the surface heating exceeds the cutting depth produced by the jet impingement. Hydraulic specific fragmentation energy values reduce by about an order of magnitude using the combination technique. The process efficiency and the rate of themohydraulic hard rock cutting increases significantly by increasing the intensity and duration of heating.

Jan 1, 1973

By J. A. Vezina

The effects of particle size distribution on metal extraction have been determined from pressure leaching Renzy Mines Limited concentrate with oxygen. Using a pulp density of 30 per cent solids, an oxygen pressure of 80 psig, a temperature of 230°F, a grind of 2.5 hours and a retention of 8 hours resulted in the almost complete dissolution of the nickel and the cobalt and the decomposition of over 96 per cent of the chalcopyrite finer than 20 microns. Only 11 per cent of the chalcopyrite coarser than 20 microns was reduced to smaller than 20 microns.

Jan 1, 1973