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By H. M. Coggin

The study summarizes the state of the art in rock mechanics, open pit and underground mining, leaching, geology, metallurgy and financial analysis Conceptual design of pit slope caving technique and analyses explore concepts for the exploitation of ore grade remnants in the walls and bottoms of open pit mines and the potential economics of the adaptations Several coded sites were examined for future studies where the feasibility of the method may be demonstrated. An extensive bibliography has been developed

Jan 1, 1977

By E. C. Stoltz

Note: An electric tin smelter for the processing of Iow-grade tin concentrates in South Africa by E. C. STOLTZ, Pr. Eng., B.Sc. Eng. (Rand) Gold Fields of South Africa Limited is the largest producer of tin in the form of concentrates in South Africa, more than 55 per cent of the South African tin production being produced by the tin mines of the Group. Most of these concentrates are exported to be custom-smelted in overseas smelters, but the modern tendency is for tin-mining countries to establish their own smelters.

Jan 11, 1976

"World Mining and Metals Technology" is the title of this year's SME-AIME Fall Meeting and Exhibit in Denver, Sept. 1-3, where a record number of exhibits are scheduled for display. The international theme is particularly appropriate, for in addition to the annual SME session, the Third MMIJ-AIME Joint Meeting will be held.

Jan 8, 1976

By Ta M. Li, Russell A. Carter

The first century of mining in northern Idaho's Couer d'Alene District will soon he drawing to a close. Like so many other great raining districts, it has been a period accompanied by a rich and colorful history. From its early days as a gold rush camp, the district has evolved into the leading silver producer in the US, but the going has not been easy: early-day labor disputes, the challenge of mining for profit in some of the deepest mines in the Western hemisphere, and the constant search for new reserves at great depths have taken their toll of mines-and miners-along the way. To these traditional mining problems have of late been added the burden of inflationary cost increases, pollution control, and reclamation. A recent visit to the district by MINING ENGINEERING, how ever, revealed that the deep commitment of the operating companies and the quiet competence and vitality of their engineering personnel are key factors in the continued prosperity of the district.

Jan 7, 1976

By T. Nagano

Mitsubishi Metal Corporation started the development work of a new process for continuous production of copper in 1961. After a series of experimental and semi-commercial operations, the first commercial plant of the Mitsubishi Continuous Copper Smelting and Converting Process was put into operation in March, 1974. The new plant, which has a design capacity of 4,000 metric ton copper per month, was built within the premises of Naoshima Smelter, replacing the old No.1 reverberatory smelter there. The SO2-rich exhaust gas from this new plant is blended with the off-gas of the No.2 reverberatory furnace for production of sulfuric acid and the overall emission of sulfur at Naoshima has been greatly reduced. The operation of the continuous plant has been satisfactory and several advantageous features of the Mitsubishi Process have been proven on a commercial scale. This paper first gives a brief description of the history of the development work and the characteristic features of the process. The paper then describes the new commercial plant and operating data obtained so far.

Jan 1, 1976

By Kevin B. Doyle

"Canada now supplies 23 per cent of the world demand for potash. Although potash is produced by many countries, Russia and Canada have the greatest reserves and capability to supply the future substantial demand over the next decade. It is estimated that demand will grow from 38,000,000 mt KCl in 1975-76 to 60,000,000 mt KCl in 1985-86. Current firm expansion plans and development underway in the world will move Russia to the forefront in supplying this demand growth. Russia will move from supplying 40 per cent of world demand in 1975 to supplying as much as 52 per cent in 1981. Canadian deposits suffer from natural disadvantages, such as high costs and risks of mine development and operation, and high-cost transportation to international markets, but experience has shown that these natural barriers can be surmounted to effectively compete in these international markets. However, Canadian potash is losing out in the race to supply the growth in the world potash demand over the next ten years because of artificial barriers raised through the unhealthy environment created by the current battle between different levels of government and the industry over resource taxation and legislation."

Jan 1, 1976

By J. F. Cornelsen

Wheel loaders are currently being used in many mining applications for a variety of reasons. While they sometimes provide the lowest loading cost, a primary advantage of the wheel loader versus other loading systems is the increased versatility and mobility inherent in a wheeled vehicle. The advent of large wheel loaders with much greater digging capability enhanced wheel loader usage in severe loading applications. To match these severe conditions, machines offered today were designed to work in these rocky conditions. Soon after the introduction of large wheel loaders into rocky conditions, however, it became apparent to many users that tire costs could at times account for up to 50% of total hourly operating costs on large wheel loaders. In some applications, tire costs alone pushed wheel loader economics beyond the economic feasibility for these jobs, prohibiting their use. In an effort to combat high tire costs, several attempts have been made to put fast moving steel around the tires to provide a strong interface between vehicle and ground. Some earlier attempts involved wrapping tracks around tires. Mechanical difficulties with these systems limited their customer acceptance. Subsequently, the development of protective tire chains came into favor. While tire chains offered added protection to the tires, the cost and maintenance of the chains remains a problem in 1972, the Dystred arrangement was announced for usage on a 6 cu yd wheel loader from Caterpillar Tractor Co. (See Figure 1). The Dystred offered the advantages of greatly increased tread life over conventional tires, as well as resistance to tread puncture in most situations. The arrangement basically employed a track system similar to that used on track type loaders. Pin and bushing wear often caused high hourly operating costs and excessive machine downtime. In addition, the connection of shoes through the use of links, pins, and bushings forced a limitation on too speed of the vehicle.

Jan 1, 1976

By Daniel G. DiCanio

This report describes a computer-based model for estimating the tangible costs of injuries and deaths from work-related accidents in underground coal mines. The study undertook to identify and quantify the elements of accident costs, including field visits to coal mines, insurance carriers, and public agencies. The mathematical models developed for each tangible element of accident cost are presented in Volume I of the report. A listing of the computer programs which comprise the model and instructions for using the programs are presented in Volume II. Statistical distributions of mining family characteristics, data on 95 miners killed in underground accidents, and other basic data used to develop the model are presented in Volume III. Application of the model to a data base of 9,286 accidents which occured in underground bituminous coal mines during 1974 yielded a total of $56,900,000 in tangible costs to industry, mining families, and public agencies. Loss of income to the families of miners injured or killed in these accidents accounted for 47 percent of the total.

Jan 1, 1976

By Leonard P. Vitt

This report details the work done to provide the U.S. Bureau of Mines with a customized Wireless Ground Monitor Wireless Ground Monitor was modified as follows: 1. A voltage regulator was added to prevent false trips with line voltage variations. 2. A Ground Wire Trap was designed to eliminate problems with parallel paths and provide spark suppression. 3. A three phase filter was designed to reduce 60 Hz leakage current. 4. A portable tester was designed to permit complete test of installed systems. 5. The design was modified to insure trip with an open ground wire in the event of a failure of any one semi-conductor component.

Jan 1, 1976

By J. F. Oyler

One of the most important applications of material handling engineering technology occurs in iron ore pelletizing plants. Although the total installed value of material handling systems in such plants, as well as in many other modern process plants, is a relatively small percentage of the value of the plants (5 to 10% perhaps), their significance is considerable. Indeed this significance equals that of the more expensive process equipment in the plant, since the failure of any component of any system causes, shutdown of the entire plant. It is because of this increased consequence of failure that design criteria for process plants are more conservative than for conventional material handling applications. A second unique characteristic of material handling technology applied to process plants in general is the variety of materials being handled and the wide range of problems this variety presents. One extreme encountered is the stickiness of filter cake. Here the entire design effort is aimed at keeping the material flowing through transfer points and preventing it from building up on components. Another extreme is the conveying of fired pellets - hard spheres with a very flat angle of repose and abrasive characteristics severe enough to make conventional wear plate materials impractical.

Jan 1, 1976

By Stig Petersson

Slag from the converting of copper matte is usually recirculated to the smelting furnace. This recirculation generally causes disadvantages as magnetite-build-up in the furnace, accumalation of impurities as antimony, lead, nickel etc in the process. The treatment of converter slag in a separate furnace in order to recover the copper and nickel content would be of advantage from several points of view. At the Mining and Metals Division, Boliden, testwork has been carried out to treat converter slag from the PS-converters in a separate furnace. The tests have been performed in laboratory and pilot plant scale. The pilot plant tests have been carried out in a TBRC with charges of 5 tons. Based on these tests a full scale TBRC has been projected in order to treat the slag from the PS-converters. This slag will be reduced with copper concentrates to give a matte and a final slag low in copper and nickel. The background and data from the testwork are presented. Also the lay out, technical data and flowsheets for the projected process are shown as well as some production data from the Rönnskär smelter.

Jan 1, 1976

By Barrie A. Wigmore

There are two aspects of financing western coal development -- whether there is going to be enough money to finance the prospective large development of the industry, and the specific techniques of raising money for that development. To take the first question of whether there is going to be enough money around to finance your industry, I think it is quite clear that the restrictions on the development of western coal are going to be non- financial. Environmental impact problems are creating the greatest delay in coal mine development, at the moment; but getting enough personnel, mining equipment, railroad equipment, and failure of the Department of Interior to act on leasing federal coal lands all appear likely to create significant bottle- necks in the development of western coal -- larger bottlenecks than financing. Financing appears straightforward for the industry. There are many projections of the financing required to meet Project Independence goals. The National Academy of Engineers estimated that development of 500 million tons per annum of western coal would be necessary by 1985 to meet the Project Independence goals which might require $20 billion of capital spending. It is generally agreed that 500 million tons a year is not a realistic possibility. Carl Bagge?s estimate of production of 250 million tons a year by 1983 appears a more reasonable projection. Development

Jan 1, 1976

According to reports in August, Botswana RST's copper- nickel-cobalt smelter at Selebi-Pikwe produced 7 percent above the rated capacity of about 3,500 metric tons of matte per month. This record production occurred after 2 years of plant production difficulties and was brought about by a new management team. A shutdown for furnace maintenance had been planned for this year, but was postponed because of the improvements in production and operations. However, the mining operation continued to face problems relating to higher costs and some outstanding claims. COPPER: Effective December 1, ASARCO, Inc. and Phelps Dodge Corp. reduced their domestic copper prices by 54 per pound. Within a period of 3 days, a11 other producers (Kennecott Copper Corp., Newmont Mining Corp., Cities Service Co. , Copper Range Co. , Duval Corp., and Inspiration Consolidated Copper Go. ) had either lowered or discounted their market postings by 5¢ to 65.625¢ per pound on electrolytic wirebar and 65$ on cathode plate. Between November 29 and December 3, New York merchants decreased wirebar quotations by 1.8¢-2¢ to within a range of 57.8¢-58¢ per pound. New York Commodity Exchange (COMEX) spot-contracted copper in the week was priced at 57. 1¢ on Monday, 56.7¢ on Wednesday and Thursday, and 57.4¢ on Friday, resulting in a 5-day average of 56.9¢, London Metal Exchange (LME) cash (prompt) wirebar averaged 56.3¢ last week, opening Monday at 56.6¢, falling from Tuesday?s high of 57.2¢ to Wednesday?s low of 55.6¢ and closing Friday at 56.1¢. Foreign producers, guided by LME market transactions, lowered wirebar quotes to 56¢ per pound. Copper stocks as of December 3 totaled 187,702 short tons at COMEX warehouses and 654,573 tons at LME depositories, compared to 97,413 and 537,481 tons, respectively, for the corresponding 1975 period.

Jan 1, 1976

By Charles Bruce

Although much has been said about the high cost of exploration, both at home and overseas, little of a specific nature has been published on actual finding costs, if indeed such data has been developed. This contrasts sharply with our sister industry, petroleum, where finding costs for oil and gas are available for virtually any country In the world. The reason is largely attributable to the genetic complexity of the hard minerals, as opposed to petroleum, and the increasing difficulties we are facing in the search for new orebodies. We have available to us data on the annual exploration budgets of most of the major mining companies which show them to run into the tens of millions of dollars. My co-panelist, Dr. Walthier, Director - Corporation Exploration, St. Joe Minerals Corporation, New York, NY, summed up the feelings of many explorationists in a recent keynote address when he stated, "I would not recommend a mineral exploration program of a general nature in North America budgeted at less than three to four million dollars annually, spread over four to five years -- or smaller amounts for more years". We have the fact that many of the major companies now prefer to "buy into" a new mineral discovery, particularly overseas, because of the high-risk and high-cost of exploration. Is there, then, a place for the small investor, let us say with a budget of under $200,000 per year and, if so, where and how? This paper is directed toward the above question and is based on experience gained while managing a limited international exploration program, on a shoestring, over the past three years.

Jan 1, 1976

If it had not been for the almost unbelievable adventures that came before and after, the last ten months of 19 15 would have been exciting enough for anyone. As it was they were a cheerful interlude. I spent most of the time on our Warren operations catching up on a lot of underground work and visiting Ajo every few weeks to see if my Chuquicamata visit might help solve the New Cornelia problem. While the difficulties were finally solved, at times they seemed almost hopeless. About all I could do to help was to make sure that the ore sent to the pilot plants represented the average ore that must be treated in the final 5000 tpd mill. Dr. Ricketts and John Greenway worked tirelessly with the best consulting advice they could obtain. Credit for the final success was due chiefly to their efforts. Since our old group had given up its "Merry Widow" home in Warren, a few of us got rooms in the company-built Cole Building over the Warren grocery store. This included Jim Lewis, Roy Mitchell, Steve Landon, Paul Stevens, and Hubert d'Autremont who came from Duluth to join our legal staff. Later we rented a small house two blocks from the Calumet and Arizona office. With the now flourishing country club only a 10-min walk away, and an electric car running to it every half hour or so, we were able to give parties in return for the hospitality of our friends. One of the most pleasant episodes came by luck a few days after I got back from Chile. Chester Congdon, a leading director in Calumet and Arizona, with his wife and their daughters, Elizabeth and Helen, spent a couple of days at the Greenway house before making an auto- mobile trip across the desert from Tucson to Ajo. At the same time I arranged to examine the small but rich Bush and Baxter copper mine a few miles from Tucson. At a party in Warren we found we would all be staying at the Santa Rita Hotel in Tucson, and I took my South

Jan 1, 1976

By Dennis J. Callaghan

This report is the result of information obtained from a review of related literature, personal inquiry and on-site examination of active surface coal mining operations. Four improved surface coal mine systems are described in detail and evaluated for feasibility, implementation requirements, environmental benefit and costs. Engineering feasibility emphasizes equipment availability, compliance to design requirements, practicality and industry rating. Implementation potential emphasizes immediacy, ease, acceptability and constraints. Special attention was given to environmental responsiveness, both with regard to the solutions to mined-land reclamation problems and to the concurrency of reclamation. Each system description includes a hypothetical model mine with a depreciation schedule, capital summary, estimated annual production costs, sales price computation, production and operating cost summary, and a sensitivity analysis of mine price to stripping ratio. A program plan and time schedule for demonstrating a selected mining system covers site selection criteria, mine data collection, criteria for controlling and budgeting costs and reporting findings. Ten additional mining methods and techniques are briefly described and evaluated. Common reclamation problems are listed and described. Sixteen state reclamation laws and regulations are abstracted. Sixty-nine references are listed in the bibliography.

Jan 1, 1976

By L. R. Plitt

A series of experiments were carried out in an effort to develop a universally applicable mathematical model of the hydrocyclone classifier. The design and operating variables studied were: cyclone diameter and height, the inlet, vortex finder and apex diameters, the feed pressure and the solids content of the feed slurry. The model consists of four basic equations which express the cut size ( dso), volumetric split between overflow and underflow, volumetric throughput, and sharpness of separation in terms of the operating and design variables. Although empirical, the model is nevertheless in general agreement with fundamentally derived models. The model clearly 1•eveals the effect of the major variables on the operation of a hydrocyclone. Because of its broad data base and the inclusion of all the major variables, the model may be used without experimental data to predict the operation of cyclones over a wide range of different operating conditions. With operating data, the equations may be modified to serve as an operational model.

Jan 1, 1976

By Cecil E. Lester

Since the advent of coal mining, the minimal lighting in the under¬ground working place has been an obstacle to the safe and efficient performance of the miner's many tasks. Compounding this problem is the fact that the machines being operated in the working place are so large that the vertical and horizontal clearances around the machinery are severely limited. Consequently, in these poorly lighted and congested working places, the machine operator is unable to utilize his peripheral vision. He cannot see hazards as they develop and, too often, cannot react in time to avoid serious injury or death to himself or his fellow miners. The greatest hazard to miners inby the last open crosscut is from falls of roof which are often preceded by warning signs such as falling rock fragments, roof supports taking weight, or a sudden reduction in the height of the working place. These warning signs often go undectected because the machine operator's attention is focused on the small circle of light emitted from his cap lamp. Congress recognized the illumination deficiencies, and, in the Federal Coal Mine Health and Safety Act of 1969, charged the Secretary of the Interior with the authority and responsibility for development and promulgation of minimum standards for illuminating working places in coal mines. These standards have been developed and, as stated in the April 1, 1976 Notice, Federal Register, Volume 41, No. 64, will be promulgated on October 1, 1976, as mandatory regulations under Section 75.1719, Title 30, Code of Federal Regulations. The regulations require that the designated surfaces within the miner's normal field of vision be illuminated to 0.06 foot-lamberts while self¬propelled mining equipment is being operated in the working places. The term "working place" is defined in the Act as "the area of a coal mine inby the last open crosscut".

Jan 1, 1976

By Lawrence M. Brennan

Early in 1971 the Peabody Design and Preparation group began engineering on a preparation plant which was to process eight mil- lion tons per year of raw coal. For the first five or six years this product was to be furnished 50% from surface mining operations and roughly 50% from underground operations. By early 1980, 1008 of the production was to come from underground mines. Because of the large annual commitment from Randolph Preparation Plant, it was essential that the plant operate with minimum down-time. As usual, capital costs were to be kept at a minimum. Before we discuss the details of design, it would be best to discuss the overall picture. Underground production to be pro- cessed through Randolph Preparation Plant was to be delivered by means of one mile overland conveyor from Baldwin #1 Underground Mine to the plant. Surface Mine production was to be delivered by means of 100-ton haulage units dumping in a 1,000-ton capacity hopper. Because of the changing production rates in both the underground and surface mines as well as the great difference in size consist, it was decided that it would be necessary to divorce the plant as much as possible from production. For this reason, twin 6,500-ton raw coal silos were constructed to separate the two coals as well as allow blending. The preparation plant itself, was to be designed to Operate two shifts per day, five days per week, at an average rate Of 2,200 tons per hour with a maximum rate of 2600 to 2800 tons per hour. Coal was to be delivered to our customers by means of rail haulage at both unit train rates and plant process rates. The surface mined coal, after discharging into the 1,000-ton R.O.M. hopper, is fed by means of two 72" wide reciprocating feeders onto a 72" wide steel cable belt. The steel cabled conveyor discharges the R.O.M. coal onto a fixed grizzly, scalping out a percent of the 6 x 0 coal. The balance is fed to a 12' x 27' Rotary Breaker. The material passing through 6" round hole screens is added to the 6" x 0" from the scalping screen. The 6" x 0" is conveyed to the top of one of the 6500 ton silos designated for surface coal. Material that is not broken to pass the 6" breaker screen is discharged to a bin and disposed of with plant refuse.

Jan 1, 1976

By Lorraine B. Burgin

This study by the Bureau of Mines documents the leadtime required for preliminary and detailed exploration, development of the mine, and construction of beneficiation and support facilities for selected copper deposits in Arizona. The time for major exploration ranged from 1 to 15 years, time for open pit development (or construction) was 1 to 4 years, and time for under- ground development was 4 to 8 years; one underground mine presently being developed may require 12 years to achieve production. Construction of the beneficiation plants required 8 months to just over 2 years. The data are supported by historical facts for each deposit during the leadtime stages from location of claims through exploration, construction, expansion, and leaching. The sequence of development and factors contributing to differences in the time spans are discussed. Histories are detailed for the Miami, Castle Dome, Copper Cities, San Manuel-Kalamazoo, and Twin Buttes properties; briefly summarized are the Pinto Valley, Miami East, Esperanza-Sierrita, Pima, and Mineral Park Properties. Each mining operation had its own pattern of development, and together they present a source of planning information for the development of other properties.

Jan 1, 1976