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By Paul H. Rydlund

The wide use of bulk ANFO in surface coal mines is questionable in our energy conscious environment. At many locations, bulk ANFO is not the proper economic selection. Water conditions, energy requirements, waste and spillage, and vibration control are factors too often overlooked in the proper choice of blasting agents. Cost savings over 20% have been realized by converting bulk ANFO to packaged blasting agents. Future trends suggest greater concern for energy conservation in blasting will limit bulk ANFO applications and promote packaged products where quality can be maximized, waste and spillage eliminated, and water compatibility in wet areas assured.

Jan 1, 1980

By Harold Potter

(1) A great deal of experimentation has been carried out by the Wet Process Cement Manufacturers in connection with additives which make possible the production of a pumpable slurry at reduced moisture contents. We ourselves have made dozens of tests both at Laramie, Wyoming and Monolith, California. (2) The viscosity or pumpability of a slurry at a definite moisture content and fineness seems to depend on two basic phenomena. One is the physical structure of the raw material itself, which on fine grinding may or may not be excessively hydrophilic (water adsorptive). Usually crystaline or glassy raw materials are non- hydrophilic. The fine grained amorphous raw materials such as shales and clayey limestones very frequently are, however. (3) The second basic phenomenon affecting the hydrophilic tendencies of the raw material is the presence of certain soluble salts, especially gypsum and small amounts of alkalin carbonates or oxides. (4) Various soaps, and phosphates can be used to produce a pumpable slurry of low moisture content when using hydrophilic raw materials as well as can other proprietary materials such as certain long chain carbon compounds. Too frequently however, the price of such additives in conjunction with the amount required prohibits their use in the cement industry.

Jan 1, 1959

By K. Sasaki, T. Murakami, S. Akibayashi, Q. Wei

A numerical analysis and an experiment were done on groundwater flow past a bore hole with a cylindrical obstacle at its center. Flow around the obstacle in the bore hole was studied in detail. Two dimensional governing equations to simulate this flow were written for the hydraulic head and seepage velocity in a porous medium and for the vorticity, stream function, and velocity in the bore hole. These equations were non-dimensionalized and solved by using the alternating direction implicit and successive-over-relaxation finite difference methods. Flow visualization experiments and velocity measurements in the bore hole were done with a two dimensional model composed of a porous medium. The numerical analysis procedures were validated by a comparison of numerical and experimental results. Effects of the Reynolds number and obstacle size on flow in the bore hole are clearly shown in the velocity and streamline profiles. The quantitative relation between the seepage velocity in the porous medium and the velocity of flow around the obstacle in the bore hole also were estimated.

Jan 1, 1996

By Thomas B. Faddies

The Trixie mine is located in the East Mining District. Since production began in 1970 over 450 000 tonnes of ore grading 239 grams of silver, 6.9 grams of gold, and 1.2% Cu have been mined from veins in Cambrian Tintic Quartzite. Detailed geologic mapping and extensive sampling are essential for compiling the data base required for efficiently developing and mining known reserves as well as planning exploration and development work. Although the basic techniques used by the geology group at the Trixie were developed many years ago, the reduced activity in underground precious metal mining in the U.S. have made these techniques less familiar to many presently active geologists. The increased activity in precious metals search and exploration again offer cause for the application of these techniques as a prerequisite to efficient exploration, development and production.

Jan 1, 1983

By Staff

Assembling consistent data for a 40-year time series is a challenge because of the many changes that have occurred in this period. In many cases, because of process improvements and consumer requirements, grades of materials change in a 40-year span. This can lead to a wide fluctuation in price data simply because of increased costs for premium grades. Sources for obtaining price data can also change during a 40-year period. Changing the data source also introduces anomalies in a time series. In some cases, published price data are not representative of the real value of the material and provide little basis for further analysis. For some industrial mineral commodities, there are only a few producers, and value and production data are considered proprietary. In the data presented in this chapter, every attempt was made to ensure that the data were as consistent and representative of the industry as possible. However, the factors mentioned above may have introduced inconsistencies in some of the data series. Many different factors influence trends for industrial minerals because of the diversity of end uses for these commodities. Trends in production and prices for most of the industrial minerals can be related to one or more of the following: changing demand or technologies in end-use industries, development of new end uses, the effect of environmental regulations, production and processing technology changes, energy costs, foreign competition and substitution by other materials, and production as a byproduct of other minerals. World economic conditions, such as recessions and inflation rates, also play a part in some production and price trends. Data for 40 years of production for industrial minerals in the United States are presented in [Table 1] in 10-year increments. Unit values for the industrial minerals, in actual and constant 1990 dollars, are shown in [Tables 2 and 3].

Jan 1, 1994

Early experiences suggested autogenous mills were difficult to operate and consumed substantially more energy than conventional rod/ball mill circuits. As our understanding has increased and the technology has matured this perception has changed to the point where most new comminution circuits are ag/sag based. In addition many operators have replaced existing conventional circuits with this technology. The JKMRC has been studying ag/sag mills for over 20 years. During this time it has amassed what is probably the single largest and most detailed data base of pilot and full scale mill operations in the world. This has been used to help develop and refine its cur- rent commercially available mathematical model of ag/sag mills. A decade of its application has greatly helped simplify both design and operation of ag/sag milling circuits as well as helping to promote the effective use of recycle crushing, secondary crushing and closed-circuit operation. This paper describes the development of ag and sag milling in terms of our understanding and the evolution of the technology. In addition the application of mathematical modelling and simulation in designing and operating efficient circuits is described with the aid of practical examples.

Jan 1, 1998

By Victor F. Hollister

The great increase in post-World War I1 use of molybdenum was made possible by discoveries of that metal in porphyry molybdenum and porphyry copper deposits. This section documents significant porphyry molybdenum discoveries of the post-war period. The most important discovery was Henderson in Colorado. It is not only one of the world's largest and richest, but it was found by a team of geologists who defined the hood model and tested it successfully at Henderson. Under the leadership of Stewart Wallace, these scientists established a set of criteria for exploration for Henderson-type de- posits that was copied by the industry. The discovery bf vertical cylinder type porphyry molybdenum deposits was less renowned. Boss Mountain in British Columbia and then Mt. Pleasant in New Brunswick were given relatively scant notice, compared with the Henderson discovery. However, these deposits have geometrics distinct from that found in the typical hood, which directly affects their exploration characteristics. Mt. Pleasant, included in this section, is a well defined, near vertical breccia pipe. Both the Henderson and Mt. Pleasant discoveries were made by relatively small groups operating independently of the bureaucracy that characterizes large corporations. The management role in each case was one of encouragement. In addition, Wallace had the beneficial experience of working for Climax, whose objective was the discovery of porphyry molybdenum deposits. Henderson was the natural outgrowth of the exploration effort by those who studied and understood the Climax deposit.

Jan 1, 1991

By J. F. Dresser

Managing environmental compliance at a complex facility has the potential to bring a high degree of personal and professional satisfaction to both the corporation and the individuals responsible for day-to-day operations. The decade of the 1990's, however, has seen the emergence of a nationwide trend of aggressive federal and state civil and criminal enforcement for environmental violations. This trend, spearheaded by the U.S. Department of Justice (DOJ) and the U.S. Environmental Protection Agency's (EPA) Office of Enforcement, has the potential to place the corporation, its corporate officers, and compliance personnel at collective professional risk, as well as a growing tendency to place accountability on individuals. Management of environmental compliance has been anecdotally compared to a shooting gallery at a carnival, with the following exception: At the shooting gallery, successfully hitting nine out of ten targets usually brings a reward and recognition of shooting skill; hitting nine out of ten environmental compliance expectations not only brings agency consternation and negative publicity, but the "gallery" will likely shoot back with stiff fines and possible criminal allegations. Faced with the challenges of the new environmental compliance shooting gallery, corporations and professionals are often left asking themselves, "How do we (or more appropriately, can we) win at this game?" This paper examines recent federal enforcement statistics and offers several suggestions for coping with the responsibility of managing environmental compliance in the 1990's.

Jan 1, 1992

By M. W. Brandt

In the November 1957 issue of "Chemical Process Engineering," a British publications, there appeared an article entitled "Correct Selection of Drying Equipment." The author wrote as follows "Whether batch drying or continuous drying' methods are applied, the basis of efficient drying is heat distribution, control of rate of heat input, and heat transference from heating medium to the particles of the material to be dried." The author continues: "Because the efficiency of direct dryers, such as hot air or hot gas dryers, increases with rising inlet temperature of the drying air or gas when exhaust temperature remains fixed, the highest practical drying temperature should be used. Exhaust air should leave the dryer at the lowest possible temperature, but as fully saturated with moisture as possible." It is certainly conceivable that the author of this article by outlining the basic requirements for efficient drying methods has unwittingly given the reasons why fluidized drying is rapidly being adopted for so many industrail applications, including the dryingof fine coal. An examination in greater detail of the individual basic requirements for efficient drying as outlined by the author is perhaps the most logical starting point.

Jan 1, 1958

By S. M. Hsiung

This paper presents the results of an extensive study concerning a series of roof falls in a room-and-pillar coal mine located in West Virginia. Three dimensional finite element modeling was employed to identify the possible causes for the roof falls. The effectiveness of possible roof control measures for alleviating or eliminating the adverse roof conditions is analyzed, discussed, and compared. The best mining alternatives are recommended. It has been found that large overburden depth and typical roof geology are the major reasons for the roof falls. Angle bolting may not solve the problem encountered in the mine studied. Changing the mine layout currently used in the mine appears to be the best alternative. The recommended pillar size and entry width which will eliminate the problem completely are 90 ft. x 90 ft. and 14 it., respectively.

Jan 1, 1985

By E. L. Michaels

Laboratory and pilot scale tests have been made to deter- mine the utility of heavy media separation, particularly a cone type separator, as a means of recovering aluminum from shredded municipal solid waste. The effect of the method of shredding on the behavior of aluminum in a heavy media system was deter- mined. Two-stage pilot scale heavy media separations were made with size fractions of shredded refuse. Recoveries of aluminum, as well as other components of the refuse, were measured and medium losses were determined. The experimental results indicate that with certain reservations a heavy media cone system can be utilized for aluminum separation and recovery from shredded and air classified municipal solid waste. Observations made using two-stage heavy media separation in a drum unit are included. Qualitatively, the results from the two types of separators are similar.

Jan 1, 1974

By William J. Halvorsen

We are currently doing work on three ways to improve the performance of our froth flotation systems. One development is the use of a cationic flocculent added to the feed of the froth cells. This does give some improvement in ash of the product particularly in a situation where there is a good bit of clay present. Difficulty is usually experienced with clay carrying over with the water contained in the froth product and also adhering to the coal surfaces. Addition of the flocculent to the flotation feed preferentially flocculates the clay causing it to drop into the tails. The results of some laboratory test work on Pittsburgh 88 Seam coal in Eastern Ohio is shown in Table 1. [ ]

Jan 1, 1979

By Hans von Michaelis

Very little has been published about Cia de Minas Buena­ventura. Don Alberto Benavides Quintana, now in his seventies, founded the company in 1953. This venerable gentleman is a Doyon of the Peruvian mining industry and more has been known about him than about his company. Buenaventura is a highly profitable gold producer with excellent potential to expand gold production in joint ventures with Newmont, Southern Peru Copper (ASARCO), and BRGM as well by developing their own new gold mines. On September 15, The Wall Street Journal published an article titled "Peru's Big Rebound Sets Off Foreign Investors' Enthusiasm."

Jan 1, 1995

By Kurt Zeidler, Vojtech Gall

London Underground Limited are currently constructing an extension of the Jubilee Line. The approximately 16-km long Jubilee Line Extension Project connects the existing Green Park Underground Station with the Canary Wharf area and Greenwich. Being a part of the project, the London Bridge Station (Contract 104) was built using a combination of the New Austrian Tunneling Method (NATM) with Compensation Grouting. NATM was successfully applied in softground and urban areas under restrictive requirements regarding settlement limitation. Information on the flexibility of the method and the influence of Compensation Grouting on ground and tunnels are given.

Jan 1, 1997

By Liang Ruilu, Guo Lihua

In light of the properties on process mineralogy of the old tailings in a certain copper mine in the People's Republic of China, a new process of combined reagent and stepwise flotation is applied in which the flotation of copper sulfides is followed by the flotation of copper oxides. Recoveries of copper and associated gold and silver have been greatly increased. The tailings obtained were subjected to the gravitational separation-magnetic separation process to recover iron minerals. Tailings from iron separation are taken as fillers and sent to the pit underground. Thus, the secondary resources are comprehensively utilized.

Jan 1, 1995

By James N. Grassby

Metal production has traditionally been a cyclical industry. 1977 in the base metals industry has highlighted that fact with a steady decline in the market place for base metals. Corporate aggregate planning is based on good forecasting and when changing conditions make that forecasting inaccurate, alternate analysis of schedules must be accomplished quickly. The computer is the only medium powerful enough to answer management's questions within an acceptable time frame. Worldwide communications networks now make it possible for the many multinational mining companies to arrive at coordinated corporate production plans based on similar basic data from several producing divisions. The Ontario Div. of Inco Metals Co., a unit of Inco Ltd., encompassed during 1977 14 producing mines, 2 nonproducing mines, 1 nonproducing open pit, 5 flotation mills, I smelter, 2 nickel refineries, 1 copper refinery, and an iron ore recovery plant. Several new mines are under development. Mine production approximates 63 500 tpd (70,000 stpd) from some 1000 workplaces. The need for longrange mine planning and scheduling is obvious and until recently has been satisfied by manual methods. However, while manual methods are often quite practical for a small number of mines, or for mines with relatively short lives, or for mines with only one mining method, the situation in the Ontario Div. is too complex and long-term to allow effective, timely planning by such methods. In 1967, a year after the first computer was installed in the division, work was begun on the computerization of the more than 30,000 borehole logs kept in the mines exploration files with a view to speeding up the assessment of mineral resources. Also in 1967 one of the first substantial systems developed on the main business systems computer was the monthly scheduling of development and production for all mines. This system encompassed tons productions per workplace, feet development per workplace, auxiliary and service activities and the requisite labor for each of these. These two dates are mentioned to show that concurrently with the acquisition of computers in the division there was an early understanding of the importance of automating mine scheduling and planning and of the potential for effective and useful computerization of such activities. In 1970, a pilot program was developed in one of the mines containing a large number of workplaces (350) to schedule the production on a network basis. Varying degrees of interest were shown by the individual mine engineers based on the complexity of the production planning problem at each mine. In an evolutionary process, mines were added to the system as its value became obvious in terms of time saving, flexibility, and accuracy. In 1975, the central mine engineering department decided that the system should be extended to all mines so that a complete division-wide long-range scheduling system would be available upon which to base development and production planning. This system would use basic ore data, allow the addition of scheduling commands, and calculate a schedule for the life of the mine. Many reports could be produced for each mine and all-mine summaries would also be available. The significance of the system can be stated in one phrase-speed, accuracy, and flexibility. Whereas in the past a long-range all mines schedule might have been done once a year, taking from two to three months, now it can be done in a day. The chief mines engineer can incorporate changes in input data and external constraints and call for a "new look" at the long-range schedule to assist him and mines production management in their decision-making processes. Using previous manual methods this could not be done quickly enough to be useful.

Jan 1, 1979

By R. A. MacGregor

The Stanreck mine of Stanreck Uranium Mines Limited in located on Quirks Lake in the Elliot lake - Blind River area of Northern Ontario. It is approximately 25 miles north of the north shore of Lake Huron, equidistant between the cities of Sudbury and Sault Ste. Marie. The property was developed ad brought into production at a rate of 3,000 tens of ore/day during the uranium boom of the mid 1950's. By 1960 mine waters were becoming quite acid through the activity of bacteria. Treatment of this water was begun for pollution control and a small amount of uranium which had been leached from the ore by these acid waters was recovered. Development of bacterial leaching with a view to increasing production by this method commenced in December 1962. Subsequently, it was succeesfull in producing 10,000 - 15,000 lbs. of U308/month. Since late 1964 uranium production has been obtained solely from bacterial leaching. A rare earth concentrate was also made for its yttrium content during 1966 and 1967. This paper describes the development, operation and methods used in the underground bacterial leaching process.

Jan 1, 1969

By R. H. T. Garnett

Reserve estimation is a process that commences with sampling and culminates in the issuance of a reserve statement. The tin, gold and diamonds that occur as marine placers on the continental shelf are low grade with very erratic mineral distributions. Sampling, using a variety of special equipment, determines the extent and grade of the mineralization. The sample size is important, especially for diamonds. Together with the sampling density, it determines the accuracy of the grade estimate. Bulk sampling is a confirmatory process. The choice of mining equipment, either new or developed from onshore activities, dictates the unit costs, the cutoff grades and the selectivity of extraction. Thus, the size of the blocks that comprise the mining plan and the reserves are determined. A variety of estimation methods of different reliability are available, with the most sophisticated being kriging. Dilution and losses during mining must be taken into account in estimation, and a grade-volume curve should be constructed. Diamond deposit estimation also involves an extra variable, the dollar value of the stones. During and after mining, essential feedback on the accuracy of un estimation may be given by the RIE factor and by a mineral balance. Reserve estimates are required for several reasons and may be subject to public disclosure. The use of the correct definitions is, therefore, important.

Jan 1, 1999

By Leonard Sargeant

The Pocahontas Coal Field consists of eight mineable seams of low-volatile coal in southern West Virginia and Virginia. The deeper seams, especially the Pocahontas No. 3 and No.4 Seams, under heavy cover and below drainage are notoriously gassy. Methane in the Pocahontas Field is generally thought of as being confined in the coal itself, rather than in mud slips or clay veins. Furthermore, it is characteristic of Pocahontas coal to retain its gas until the coal is broken and removed from the solid. Because of this inability for gas to escape from unmined coal, entries developed around large blocks are seldom of significant value in bleeding off methane before pillar extraction begins. This is evidenced by the fact that it is not uncommon to find gas liberated during the mining of chain pillars and barriers which have been developed for several years. The Pocahontas Fuel Company develops almost all solid coal by conventional methods with shuttle car haulage. To provide the maximum productive capacity without compromising ventilation and safety requirements, the Company has adopted standards for ventilating 5, 6 and 7-entry sections.

Jan 1, 1960

By William W. Kephart

Brockway Glass Company, Inc., manufactures glass containers at fourteen plants located in nine states. The relatively high place value of the major glass batch components dictates that raw material supplies be obtained from numerous sources in the United States and Canada. One objective of our central composition control program is to arrive at a glass composition with similar physical properties at each of our plant locations. This requires that adjustments be made in the batch compositions to compensate for chemical variations from one raw material source to another. Minor chemical variations will occur in sand, limestone, and dolomite from one source to another. Major variations are present in the alumina sources because of the diverse rock types utilized.

Jan 1, 1973