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By Charles L. Elliot

Data on worldwide geophysical activity in application to mining exploration programs is collected annually as part of a continuing service to the mining and petroleum industries. The data for mining geophysical activity in 1966 has been made available to SME by the Society of Exploration Geophysicists. This data is based on 288 voluntary responses for a return of 59% to 487 questionnaires that were circulated among worldwide mining companies, universities, and government institutions that conduct or utilize mining geophysical surveys or carry out allied research efforts. This data is herein published in condensed form with the permission of the SEG.

Jan 11, 1967

Kennecott Copper Corp. has sub- mitted a proposal to the U. S. Atomic Energy Commission for a joint experiment to determine if a contained underground nuclear explosion can be used to fracture a low-grade copper ore deposit to recover the copper by in-situ leaching. If authorized, safety and technical studies in the field would be undertaken to determine whether such an experiment could be conducted with full protection for public health and safety. The proposed experiment, known as "Sloop," would be part of the AEC's Plowshare Program to develop peaceful uses of nuclear explosives. As now visualized, the project involves the detonation of about a 20-kiloton nuclear explosive at a depth of 1200 ft.

Jan 11, 1967

By H. N. Egan

Faced with a severe disposal problem of their fines from a coal mine in the heart of the Appalachian Mountains of extreme eastern Kentucky, Eastern Coal Corporation has built a special plant to pelletize the fines into high quality coal pellets meeting the requirements of the metallurgical market. These low-ash, low-sulfur pellets measuring 3/4 x 3/8 in. contain less than 1.5% moisture and have the same stability as raw coal of the same size. Although Eastern Coal is mining 6000 tpd, the company had, until recently, no provision to recover the fine coal which was included with the plant effluent pumped to a 12-acre refuse pond. The pond, impounded behind the coarse refuse dump, rose 15 ft last year and obviously no pond can stand many years at this rate. Limited pond space in this rugged area of steep hills and narrow valleys dictated a revised disposal method.

Jan 11, 1967

Shoemaker: We've all heard a lot about epoxy liner backings. This brings up the question-do zinc furnaces still have a place in a new plant? Meaders: I would, you must understand, be prejudiced in this question because we introduced epoxy backing into the industry. Naturally, we wouldn't have done so if we didn't think it should be done. With that background maybe I could give a little more information on this particular subject than some of the others, because we now have been in this business for some three or four years.

Jan 11, 1967

A development drilling and bulk sampling program should furnish the following information: (1) geology of the mineralized zone, (2) quantitative data on grade and tons of material within pertinent cutoff limits, (3) physical size and shape of the deposit and areas underlain by waste as well as ore, (4) mineralogical and metallurgical characteristics of the ore, (5) physical characteristics of the ore, (6) bulk samples for metallurgical testing and grade, (7) data on factors that affect mining operations, such as ground water and ground conditions. The method and equipment best suited for a particular drilling job depend upon the geologic features of the mineral deposit to be tested.

Jan 10, 1967

Planning for a surface coal mine includes selecting the best means and equipment for uncovering the coal, loading it, and transporting it to the preparation plant. The machines and methods that will ensure optimum production will depend upon the location and characteristics of the seam to be mined. Stripping Techniques The choice of stripping units is influenced primarily by the system of mining, such as contour or out-crop mining as contrasted to mining in a region of rolling terrain with relatively flat upland surfaces. Factors such as the life of the mining operations production requirements, types of overburden, local and regional dip of coal, and land reclamation are other important considerations.

Jan 10, 1967

As knowledgeable men in the industry know, a mineral occurrence is found through prospecting but an ore deposit is "made" -made through, first, imaginative and effective exploration; thence through efficient engineering, sales and management. There are two main phases of exploration-reconnaissance and target investigation-each of which can be further divided into two additional stages (see accompanying table). The search for a new ore deposit within a known and geologically mapped mining district involves only the last two stages, whereas the search for a new orebody in a virgin geologic environment involves at least three stages and often the full sequence. Of course, some of the exploration stages may be bypassed depending on available results of previous mineral surveys and/or exploration by individuals, business concerns, and governments.

Jan 10, 1967

Electrical requirements in surface mining can be divided into three categories: main substation, plant power, and pit distribution. A main substation may vary from a 500-kva transformer supplying 480-v power to motor-driven pumps and conveyors, to a 50,000-kva substation serving a large beneficiation plant or a large strip mining operation. Regard- less of size, it should be designed with the realization that a failure of the main substation will totally shut down the operation. Location of a main substation usually is a compromise between expense of running the incoming high-voltage transmission lines and the voltage drop of long secondary runs. Based on a geological survey for immediate and future areas of excavation, the main substation should be located as near to the center of load as possible.

Jan 10, 1967

There are two types of shovels currently used primarily as mining tools-the stripping shovel and the quarry-mine (Q-M) shovel. The two types have basically the same features, the main difference being in size. The stripping units are giant four-crawler shovels that operate by placing overburden alongside in a mined-out area. The Q-M units, on the other hand, are two-crawler shovels that usually load into trucks or trains. Powering Systems A typical stripping or Q-M shovel is fully electric, receiving power through a trailing cable that is connected to a large motor-generator set with multiple generators. In the full Ward-Leonard system, each generator furnishes d-c power to separate motors which drive the mechanisms for the principal motions of the shovel-hoist, crowd and swing.

Jan 10, 1967

For handling rough rock, the shovel-train system is unexcelled. The ideal application is a physically large, but not excessively deep, open-pit mine from which the coarsely blasted ore and waste must be transported distances in excess of three miles. If, in addition, a high production rate is to be maintained, railroad haulage will probably afford a lower cost per ton transportation than will any other haulage method. Relatively gentle grades must be employed- usually 3% for uphill hauls and 4% for downhill hauls. The greater the differences in elevation the greater are the railroad track grade space requirements. By way of illustration, a 3% ramp out of a pit only 300 ft deep must be almost two miles long. Mainline track locations should be selected carefully so that the frequency of movements during the life of the mining operation is minimized. This applies both to ore and to waste haulageways. Such moves are not only expensive but difficult to execute without adversely affecting production rates. The large mine affords greater opportunities for judicious location of semi-permanent trackage.

Jan 10, 1967

The history of surface mining is essentially that of mining coal, copper, and iron ores and the non- metallic minerals, i.e. clays, gypsum, phosphate rock, sand, gravel and stone. The accompanying table comparing world production with that of the U. S. indicates that two thirds of the 8.8 billion tons of ores mined throughout the world come from surface operation. Assuming that the stripping ratio for surface mining in the U. S. applies equally to world production, then over 21 billion tons of waste, or a total of nearly 27 billion short tons of material are mined annually in the world by surface methods. Several factors are significant indicators of economic and technologic trends in surface mining. Among these are increasing production, a shift in emphasis from underground to surface mining, a decline in the grade and quality of some crude materials and, with few exceptions, an increase in the productivity of labor.

Jan 10, 1967

In any earth-moving operation, more profit may be earned or lost by equipment scheduling than by any other single facet of the project. Many now-defunct earth movers would have survived the cost-profit squeeze had they followed an efficient, cost saving, equipment scheduling program. The ideal program would have every item of the equipment fleet working all of the time. In practice this ideal situation is not possible. Several basic methods of equipment scheduling, with an infinite number of minor variations, are used. The first approach is the use of a "minimum equipment fleet," of which all items or equipment are scheduled each working shift.

Jan 10, 1967

Key elements of open-pit design fixing the ultimate pit limits are stripping ratio, pit slope angle, and grade cutoff. Results of exploratory and development drilling should be reduced to horizontal sections corresponding to level spacing. It is advisable to interpolate the actual drillhole values to a uniformly spaced 50-ft grid system. Vertical sections can be and are used to approximate the fixing of pit limits, but horizontal sections must be used to optimize a pit design. To develop a pit design requires the establishment of the break-even stripping ratio. This ratio is applied only at the surface of the final pit and must not be confused with the over-all ratio, which is always less; otherwise there would be no profit in the operation. The break-even stripping ratio is determined by the formula: [ ]

Jan 10, 1967

The selection of a particular machine for production drilling is the most critical drill evaluation the pit engineer is called upon to make. It is a true engineering design problem requiring value judgments. Generally, the procedure follows these steps: (1) Determine and specify the conditions under which the machine will be used, including such service factors as labor, site, weather, etc. (2) State the objectives for the rock-breakage phases of the production cycle of operations--considering excavation and haulage restrictions, crushing capacity, production quota, and pit geometry-in terms of tonnage, fragmentation, throw, etc. (3) On the basis of blasting requirements, design the drill-hole pattern (hole size and depth, in- clination, burden, spacing, etc.) (4) Determine the drillability factors and select the drilling methods which appear feasible for the kind of rock anticipated. (5) Specify the operating variables for each system under study, considering drill, rod, bit and circulation fluid factors. (6) Estimate and compare performance parameters, including costs. Major cost items are bits, drill depreciation, labor, maintenance, power and fluids. (7) Select the drilling system that best satisfies all requirements with the lowest over-all cost.

Jan 10, 1967

The fundamentals of blasting involve both the properties of explosives and of the rock being blasted. Four of the most important explosive properties appear to be energy density, bulk density, rate of energy release and the pressure- time history of the gases produced. Important rock properties are density and porosity, strength, and energy absorption including the effective moduli of elasticity. Rock structure also has a marked effect on its properties: for example, joints, bedding, and fracture alteration. Several mechanisms enter into rock fragmentation by blasting. These include slabbing, radial fracturing, crushing and bursting by the gas bubble. All of these factors are closely related to properties of both explosives and rock. Slabbing depends upon the first generated stress wave, whose shape and magnitude are a result of the pressure generated by the explosive, its time history and the resultant response of the rock, including its ability to sustain the stress wave. Actual slabbing, in turn, is a function of the magnitude and shape of the pressure pulse and the tensile strength of rock. Further fragmentation depends to a great extent upon the amount of gas in the bubble and its energy and pressure.

Jan 10, 1967

Some specific observations might be appropriate concerning the reporting of Research and Development results. Each report is usually directed towards a particular group, such as technical, operational financial, or marketing. The requirements and background of the group receiving the report must be considered, and the emphasis and coverage geared to the training of people concerned. For reports that might have large and varied distribution, it is often feasible to group, either as sections or appendixes, the special details and information of interest only to certain functions within the organization. (A check list prepared in conjunction with the various users of the report is sometimes useful to prevent omissions.) Typical points listed might be: Financial- (1) capital requirements, (2) timing of capital expenditures, (3) tax implications, including depreciation, depletion and investment credits, (4) changes in working capital.

Jan 10, 1967

By L. C. De Jong, J. F. Shirley, M. L. Campbell

The Toquepala concentrator of the Southern Peru Copper Corp., located approximately 720 miles southeast of Lima near the Chilean border, processes 36,500 tons of ore daily containing between 0.50% and 3.00% copper. The molybdenite content in the ore also varies greatly, ranging from essentially nothing to as high as 0.15%. The 1966 yearly averages were approximately 1.20% copper and 0.03 % molybdenite. The three basic problems that plague the opera- tion of any molybdenite recovery plant are all present at Toquepala in large measures. Both the quantity of plant feed and the quantity of molybdenite contained in the plant feed are continuously changing. Even more detrimental to an efficient operation is the fact that the copper mineralization in the feed frequently changes once in every 24 hours and occasionally once a shift. From the point of view of the molybdenite plant metallurgist, there are four distinctive chalcopyrite concentrates and, at least, an equal number of chalcocite concentrates treated in the molybdenite recovery circuit. The various types of concentrates are distinguished mainly by their mineral content and how effectively the copper minerals are depressed by the different reagents used in the circuit.

Jan 9, 1967

By M. Safiuddin

Within the mining industry, open-pit mining has progressed to a point where a 200-yard walking dragline is as conceivable today as a 35-yard dragline was just a few years ago. This is possible due to the technological advances and efforts of the excavator manufacturers, and the manufacturers of electrical equipment have always stayed abreast with them in meeting their requirements and in making available their experience with the latest control techniques and hardware from various fields for application in the mining industry. An electrician in the coal mines of Pennsylvania who had not heard the word "thyristor" a few years ago now wonders how the old excavators with Rototrols® and magamps could ever work. The thyristors, transistors and operational amplifiers which were considered too fragile and delicate for a rugged and severe application like the mining industry, today constitute the brain of an excavator control taking commands from the operator and giving signals to the muscles of the excavator to move the bucket within a few seconds. A giant 200-yd bucket filled with overburden moves within seconds of the operator's command. Digging cycles for these excavators range from 40 to 60 sec depending on the swing angle. With these tremendous production capabilities of the excavators, the equipment failures and downtime become very expensive, and the loss of return on large capital investment for such machines becomes intolerable. Even though these failures and downtimes cannot be avoided completely, a good preventive maintenance program can help reduce them, thus increasing the machine availability. As we shall see below, the causes for breakdowns and failures of electrical equipment can be analyzed and a good preventive maintenance program can be drawn up to eliminate most of these failures.

Jan 9, 1967

R. S. Shoemaker: Our first question is, is there a need for a grizzly before a primary crusher? What is its effect on crusher capacity and crusher maintenance? Is it worth the extra capital cost in a crusher installation? Vincent: ASARCO has a grizzly at Mission. Utah Copper uses grizzlies ahead of their gyratories. There is some quite abrasive ore at Mission, an argillite type of rock, which has a work index of 16.5 to 20, which is getting up toward the taconite classification. We get a life of 12- 16 million tons per set of concaves or per mantle with the grizzly ahead of the crusher. At Duval Corp., some 6 miles to the south of Mission, their crusher installation on a good, hard rock does not have a grizzly, and the last information I had is they get a life of about 2 ½ -3 million tons on their mantle and concave. At Silver Bell, our other copper unit in Arizona, they do not have a grizzly ahead of the gyratory and there they get a life of about 5-6 million tons. At Utah Copper, which we all know is a fairly soft ore, relatively speaking, they get a life of 24-27 million tons with grizzlies ahead of the crushers. I think a grizzly has a very definite effect on the life of the mantle and the concaves. As far as a jaw crusher is concerned, I think that usually it is desirable to have a grizzly if it is properly designed, which means it is self- cleaning. Otherwise I would not like to see one in the circuit.

Jan 9, 1967

By August E. Vandale

Mining of the Freeport and Pittsburgh coal seams in the Pittsburgh vicinity dates back more than 100 years, and Consolidation Coal Co., or its predecessor, Pittsburgh Coal Co., has been actively mining in the area since 1900. Over the years, Consol has acquired good legal title to the coal lands purchased from individual farm owners, with broad mining rights, and in 98% or more of its title holdings, the company has a complete waiver of surface damage or the right to subside the surface land. (Titles in Pennsylvania can be in three forms: title in fee; title to the mineral; or mining rights permitting the removal and extraction of the mineral with or without waiver of surface damage.) In the early history of Consol, individual farms overlying the seams were purchased from land owners. Many of these titles severed the coal estate from the "in fee" title, and mining rights with waiver of surface damage were conveyed in the original severance deed. In this manner, Consol was able to put together its large mineable coal reserves. Consol has practiced "full recovery" mining as far as practical from its early years of hand loading to the recent era of mechanization.

Jan 9, 1967