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By Fred T. Towne

There are a number of air classifiers manufactured throughout the United States and the rest of the world. The classifiers manufactured by Alpine, A. G. of Augsburg, Germany, are unique in their abilities. It is this uniqueness that I wish to delve into and in this respect we will limit this discussion primarily to the classifiers as manufactured by Alpine. It has been reported in the past that these classifiers were introduced into the. United States in the late 50's. Until the introduction of the Alpine Classifiers, air classification seldom produced a satisfactory fractionation of a product below 45 microns (325 mesh) or above approximately 22 mesh. It has been a common practice to classify fine materials which used water as a carrier medium The use of centrifuges are today producing thousands of tons of finely partitive powders in the very small particle size range. The use of centrifuges in connection with wet grinding mills has increased the rates of production of these mills considerably.

Jan 1, 1965

By Wallace W. Wilson

It scarcely 1s possible to read a new issue of any of the principal mining trade journals without noting some mention of a major new overseas mining venture with which one or more domestic companies are involved. These projects seem to follow a fairly consistant pattern; most are large open pit mines, with relatively low grade ore bodies but huge reserves; the total price tag will be in nine significant figures and around half or more of the total cost will be for infrastructure. West1 noted that nearly $7 billion is being invested annually for new mining projects and the expansion of existing mining ventures, in the free world. He anticipates that by the year 1975 such investments would reach the $10-11 billion annual figure, and that in the five year period 1972-76 total capital requirements can be expected to aggregate around $45 billion. The proportion of this total investment which will be financed in some manner is difficult to estimate because of the variety of available financing arrangements. West estimated that around 75% of the total capital would come from internally generated funds, with the balance from external sources. Conceivably a substantially higher percentage could be attributable to external financing, especially it the trend of recent mineral development in Canada and Australia is any criterion, and of course, including local sales of equity as a part of the package.

Jan 1, 1973

By I. K. Choi

In a recent paper by Smith and Wen(1) the adsorption of sodium dodecylsulfate and trimethyldodecylammonium chloride on kaolinite was studied. As would be expected considering the general negative character of kaolinite, except perhaps at quite' acid pH values (2,3,4), it was found that trimethyldodecylammonium chloride adsorbed strongly on kaolinite at basic pH values. Furthermore, it was found that sodium dodecylsulfate adsorbed strongly on kaolinite at acid pH values, particularly at initial 1H values below pH 3 (final pH values near pH 4). It is interesting to note that adsorption of the anionic surfactant was strong under conditions where the kaolinite was apparently slightly negatively charged (2). The present paper reports on an extension of the work by Smith and Wen. In this paper the effects of the presence of dodecyl alcohol and sodium hexametaphosphate on adsorption of sodium dodecylsulfate and trimethyldodecylammonium chloride on kaolinite are considered.

Jan 1, 1967

By Erik A. Munroe, Nelia W. Dunbar, Virginia T. McLemore

In New Mexico, there are at least 100,000 abandoned mine waste rock piles with widely ranging geochemical and mineralogical compositions. A geochemical and mineralogical study was implemented for five waste rock piles, some which contained sulfides, in the Hillsborn Mining District. Chemical and physical characteristics of mineral grains and their secondary mineral oxidation rinds were examined with the electron microprobe. Pyrite and chalcopyrite appear to be the most reactive to oxidizing conditions. Clays, iron oxide, iron hydroxide, iron sulfate, and primary texture rinds exist in the waste rock piles analyzed.

Jan 1, 2000

By James A. Clum

The shift to lower grade iron ores, e.g., magnetic taconites, resulted in a shift towards agglomeration practices which could effectively deal with the fine particle sizes generated in the liberation and concentration processes. If the iron bearing particles are not extremely fine, e.g., -1/2 in + 100 mesh, sintering is an adequate means of agglomeration.(1) For the more dispersed ores which result in fine concentrates (more than 80%,-325 mesh), the fine particles must be agglomerated by mechanical means before final hardening, e.g., pelletizing.(1) In the pelletizing process, the essentially mechanical step of balling is extremely critical since the strength of the pre-fired pellet determines the firing conditions. The ability of the proper amount of moisture to hold together a ball of the very fine ore concentrate particles has long been recognized. It is a charac¬teristic of the reaction at the interface between the ionic solid of the ore concentrate and the polar water phase which overlays the solids. The strength in such moisture laden balls, the green strength, is a strong function of the water content (Figure 1) and thus deteriorates rapidly for either a small excess or a small deficiency of moisture. For purposes of commercial practice, the control of green ball handling properties by accurate control of ball moisture is too demanding. Moreover, as the ball is heated towards its hardening tempera¬ture, e.g., 1300'C, there is a substantial drying reaction which would lead to such a low dry strength of the ball that it would not support its own weight much less the weight of other balls in a firing furnace.

Jan 1, 1976

Strainburst phenomena, generally characterized by a sudden release of energy in a volume of highly stressed rock, are often encountered in such situations like crown pillar bursts in cut-and-fill mining, face bursts at development headings and floor bursts in deep shaft sinking. This paper describes a simple FE modeling approach which leads to the calculation of the energy release rate (ERR) and the total energy storage rate (TESR) in the rock mass around the openings. The merits of using such energy parameters in the analysis of strainburst problems to identify areas of high energy release/storage are discussed. However, much site-specific back analyses are needed to better understand how strainbursts and energy parameters are inter-related.

Jan 1, 1998

By R. Jin

The hydrophobicity of six coals ranked from lignite to anthracite is studied through contact-angle measurements, bubble attachment-time measurements, FTIR spectroscopy, and Hallimond-tube flotation. The preliminary study shows that the hydrophobicity of coals can be told by the bubble attachment times of coals (a kinetic criterion) or by the contact angles (an - equilibrium criterion). A general agreement between flotation response of coals and measured bubble attachment times or contact angles is observed in the present study. However, the study also shows that the hydrophobicity of coals can be predicted by FTIR spectroscopy work with proper manipulation of the spectra. Both hydroxyl and carboxyl groups in the coals are proven by FTIR work to be responsible for the change of coal hydrophobicity. A new criterion for the hydrophilicity index of coals from FTIR spectra is introduced through the study.

Jan 1, 1987

By Thomas Novak, Philip Johnson, Richard L. Sanford, Lloyd A. Morley

Macintosh use in mine-planning applications lags DOS machines since many users have made significant investments in hardware and training for other environments. Macintosh use is becoming more pronounced in many other industries, and com soft-ware is of at least the quality of that available for DOS machines and many workstations. This paper describes attributes of the Macintosh computer family as related to many mine-planning problems and solutions including software, memory considerations, workstations, DOS compatibility, and networking.

Jan 1, 1993

By Paul C. Lingo

The title of my talk today might lead you to two logical conclusions: The industry is faced with a problem that requires a solution and after discussing the problem I will offer a solution. The first conclusion is painfully accurate. One need only look at the accident statistics to be aware of the problem. During the eight-year period 1954 through 1962, the United States Bureau of Mines reports that falls of rock and coal accounted for 1,435 of the 2,516 fatal injuries that occurred in underground bituminous coal mines. Some improvement was made during 1962. For the first time since records have been kept, falls of rock and coal accounted for less than 50 per cent of the underground fatal injuries. The 105 deaths recorded in 1962 indicate that a great amount of work remains to be done in this area. As to the second conclusion, let me assure you at the outset that I have no panacean solution; however, I do propose to discuss some aspects of the problem and some possible methods of solution. What methods of solution are now, or have been employed in attempting to solve the problem? More specifically, what methods have you and your associates used? Has it been an orderly well thought out approach to the entire problem, or has it been a somewhat piecemeal approach which tackled the immediate problem and left the total problem for another day? Perhaps a new approach may be in order.

Jan 1, 1964

By G. A. Hayes

The range of gold ores tested at AMMTEC LTD over several years has resulted in the requirement to analyse for the mode of occurrence of gold in order to assist selection of ore processing options. The aim of this paper is to describe the laboratory testwork and analytical procedures which have been of benefit in detail­ing the mode of occurrence and mineral associations of gold and hence being of value in developing an optimised ore processing route. The range of ore and mineral assemblages described include relatively simple pyrite and free milling ores, more complex pyrite plus arsenopyrite gold ores and the quite com­plex associations of gold in copper bearing ores or with car­bonaceous mixed sulphide ore assemblages. The aim of this paper is to describe the laboratory testwork and analytical procedures which have been of benefit in detail­ing the mode of occurrence and mineral associations of gold and hence being of value in developing an optimised ore processing route. The range of ore and mineral assemblages described include relatively simple pyrite and free milling ores, more complex pyrite plus arsenopyrite gold ores and the quite com­plex associations of gold in copper bearing ores or with car­bonaceous mixed sulphide ore assemblages.

Jan 1, 1996

By A. J. Neale

Much has been published lately about the application of advanced control strategies in the automatic control of autogenous and semi-autogenous grinding circuits. The application of adaptive control algorithms, self-tuning controllers, state estimation, and expert systems has been well documented. While these approaches can be very effective; experience has shown that quite often simply "fixing the fundamentals" can have a significant positive impact on overall grinding circuit performance. This paper will highlight the results of process optimization and process control work by the authors at a variety of autogenous and semi-autogenous installations. A review of one approach for quantifying the mill load/bearing pressure/power relationship is provided. Accurate monitoring of key mill process variables is a necessary prerequisite for both effective process analysis and process control. This paper discusses some of the concerns related to defining steady state operating conditions and the issues related to signal conditioning. The paper concludes with a discussion of an effective application of algorithmic constraint control which incorporates many of these considerations.

Jan 1, 1994

By D. W. Frommer

In continuing its long range studies of methods of treating low-grade iron ores, the Bureau of Mines has developed a new selective flocculation, desliming, and flotation procedure that enables effective beneficiation of the finely disseminated ferruginous jaspers of the Marquette range, Mich. The process, developed on a bench scale and later confirmed in the 800-lb/hr pilot plant, comprises dispersion, selective flocculation, desliming to reject fine silica and clay, and flotation of silica from the remainder of minus 400-mesh pulps. Pilot plant flotation of two Marquette range ores, using the selective flocculation procedure on feeds containing 36 percent Fe, yielded iron recoveries of about 84 percent in concentrates containing 65 to 66 percent Fe and 4 to 5 percent silica. These results were metallurgically superior to those obtained when selective flocculation was not used. Also operating characteristics were better, and reagent costs were lower.

Jan 1, 1964

By R. L. Hills

America's industry uses about 44% of the total energy consumed by the nation directly as fuel burned in industrial plants or indirectly as fuel burned by utilities to provide electric power. In addition, industry requires raw materials or feed stocks derived from fuel sources or having fuel value. This represents about 11% of total U. S. energy consumption, bringing industry's portion to about 55%. Adding that portion of energy consumption required by the transportation sector to move raw materials, intermediates, and finished products, the total energy impact of industry approaches 213 of total U. S. consumption. It is obvious that American industry has the largest share in the task of balancing energy demand and supply. What are we going to do? -- We must increase the supply of energy and increase the beneficial results obtained from each unit expended. Both avenues, unfortunately, are limited in extent and speed. Increases in supply cannot occur without drastic and permanent increases in cost. These increases in cost are un- desirable and inflationary but do provide incentive for the rational businessman to expend the effort and money required to improve the effectiveness of energy in industry.

Jan 1, 1975

By William N. Poundstone

Since World War II, when off-track mining became popular, mining machinery has undergone much change. However, the change has been basically to make the machines more powerful, more productive and more reliable. Little change has been made, in this period, in the basic mining system. While steady improvement was made in productivity until the passage of the new Federal Coal Mine Health & Safety Act, I believe that the cost Co benefit ratio of further improvement from this basic approach of improving the existing extractive tool is not as promising as I believe may be obtained from a new approach. Consequently, six years ago Conoco and Consol undertook a comprehensive long-range R&D program to see if improvements of a more basic nature could be made in underground mining. We concluded early in our program that while many things currently limit the rate of production such as the rate at which roof can be supported, time needed to advance ventilation systems, time required to clean up and rock dust, time required to maintain and service equipment as well as time lost due to haulage deficiencies, that the key to improvement was a truly flexible continuous high capacity haulage. With face equipment in use today, mining rates can be increased with such a haulage system where the ability to support the roof exceeds the ability of conventional haulage equipment to remove the coal. More importantly, if we could develop such a system, it would set the stage for development of far more sophisticated methods of mining at the face than exist today, and as new and more dependable mining machines and methods are developed, continuous transportation will enable the gains envisaged in production to be realized.

Jan 1, 1974

By Stanley J. Gasior

Most bituminous coal mined near Eastern industrial areas requiring high Btu pipeline gas is caking and therefore unsuitable for fixed-bed pressure gasification by present techniques. If the caking property of such coal can be destroyed the resulting fuel can be gasified in a fixed bed at pressure with steam and oxygen as a preliminary step in making a high-Btu gas. To find a practical way to convert strongly caking coals of granular or small lump size to noncaking fuel was the object of this study. In previous work strongly caking coals of 1/8- to 1-1/2-inch size was converted to a noncaking coal char by treatment in a static bed in about 3 hours [1/]and coal of 18-100 Tyler mesh in a fluidized bed in about 5 minutes.[2/] An inert gas such as `steam, nitrogen, carbon dioxide, or a mixture of all three with a small amount of oxygen was used in both studies. In our work a strongly caking bituminous coal from the Pittsburgh seam of 4-8 Tyler mesh size was converted to a-noncaking form in free-fall in about 2 seconds by dropping it through a countercurrent flow of steam containing 4 to 7 percent oxygen at 1,150°-1,200° F and 300 psig. This method should also be applicable to smaller-sized material.

Jan 1, 1965

By James L. Vanderbeek

INTRODUCTION Semiautogenous (SAG) grinding technology first started to be seriously considered for comminution circuit design in the mid-1960s as an alternative to the three-stage crushing circuits and rod-ball mill circuits in vogue at the time. Since this time the application of SAG mill technology has become widespread with over 250 mills larger than 20 feet in diameter sold (Jones 2002). The vast majority of concentrators constructed over the past quarter century have utilized SAG mill technology, and a SAG-based comminution-based circuit is generally the first choice considered for new projects. Since the first generation of SAG milling technology was applied, many lessons have been learned, and new supporting technologies have emerged which make the design, installation and operation of SAG &-based grinding circuits more robust and efficient. This paper will discuss the current status of SAG and associated technologies. MILL MECHANICAL DESIGN ISSUES Table 1 summarizes the manner in which SAG design capability has evolved over the past 30 years. Increases in mill diameter came slowly as the industry took a wait-and-see attitude as the technology of larger mill diameters was advanced. The first 32-foot- diameter mill was ordered in 1969. It was not until 1979 that the technology jumped to the 34-foot-diameter mill and 1988 for the first 36-foot-diameter mill. The first 38- and 40-foot-diameter mills were both ordered in 1996. At least five 38-foot-diameter and two 40-foot-diameter mills will be in operation by mid-2004. Advances in structural analytical techniques and increased computational power, coupled with field measurements of large operating mills, have increased the confidence of the mill suppliers in their designs and the operating companies in the viability of larger diameter mills. No failures of a 36-foot-diameter mill or larger have been

Jan 1, 2004

By R. F. Davis

The evaluation and selection of coals for producing metallurgical coke is indeed a com- plex process simply because coal is a complex and variable substance which is sensitive to how it is treated from the time it is mined until it is transformed into coke. A review of the the more common evaluation tests made on coal and how the test results are applied in commercial practice. Parameters used to select coal blends for wet and preheated charges should also be of interest.

Jan 1, 1980

By Richard O. Rouse

Today, I want to challenge this audience by charging each of you to be a greater manager and superior engineer to manage and engineer our way through the 1980's and profitably overcome all the present and proposed government regulations. May of the present and proposed regulations will tax you and your company's management and engineering to the brink of physical and monetary exhaustion, but I believe we can succeed and coal can be America's answer to her hungry energy needs. To put our 1980's challenge into perspective, I want to give two great challenges we must overcome. First - We must improve on our process of compliance to new government regulations in the technical and equipment end of our industry. The Lord said, "Let There Be Light". MSHA said, "Let there be light in underground coal mines". Since that time, we have lived through an unmanageable and tremendously costly period of compliance.

Jan 1, 1980

By R. L. Atwood

This paper discusses the metallurgical and Manufacturing input to Merrill-Crowe plants. Topics treated are pregnant solution chemistry, clarification, degassing, zinc addition, product filtration, accounting, and costs.

Jan 1, 1985

By Richard C. Sale

INTRODUCTION The topic of the paper is to discuss the use of micro computers in the construction industry. I will first discuss the present situation of the PCs in our industry followed by a discussion how Guy. F. Atkinson has integrated the PCs into it's organization. I will close with some general comments that any organization should review in order to enhance the use of their PCs both at the job sites and home office locations. PRESENT SITUATION OF THE PCs IN OUR INDUSTRY Today, the possible number of combinations that can be obtained when bringing together the available models of PCs, with their peripherals and software, is astronomical. With this array of equipment that can be bought, plus the new and possibly better equipment that is being put on the market almost daily, it is indeed a very difficult task for an organization to know how to invest its money in computer equipment. At the job sites, the work is fast paced with little time available to fully learn what the PCs can do to help with the required paperwork. I am still waiting for the day when someone has to tell the superintendent at the job site that he cannot start pouring concrete or shoot the next round because no one can get the computer to work.

Jan 1, 1987