Search Documents

By G. P. Pilling

The use of magnetic ore in the blast furnace is a subject of increasing importance. The end of the deposits of lake ore is in sight, although not imminent, and unless some new field is discovered, the use of magnetites will be an increasing factor in the iron production of the country. Enormous deposits of magnetic ore in the country that have been practically untouched contain ore of sufficient richness and purity to prolong materially our ore supply without extensive importation of foreign ores. Magnetic ores can be divided into three general classes: Fine un-sintered, or raw ore; raw lumpy ore; fine ore that has been sintered. Fine Unsintered Ore Typical analysis and screen test of this class of ore from the Adirondack region is as follows: Per Cent. SCREEN TeST pER Cent. Fe.................... 58.00 Remaining on 4 mesh........... 7.50 SiOz.................. 7.50 Through 4 on 8 mesh........ 13.75 Al,O,................. 1.60 8 on 10 meah........ 3.75 Baseg................. 2.77 10 on 20 mesh........ 22.50 P.................... 1.00 20 on 40 mesh........ 27.50 Mn................... 0.13 40 on 60 mesh........ 2.50 S..................... Trace 60 on 80 mesh........ 10.00 80 on 100 mesh........ 2.50 100 mesh........ 10.00 100.00

Jan 1, 1923

By Keith Leonard Sutherland, Ian William Wark

Mercaptobenzthiazole and its sodium salt are marketed under the trade names Flotagen and Flotagen S respectively, for use as collectors for cerussite and other minerals. The structural formulas for sodium rnercaptobenzthiazole and for sodium ethyl xanthate are: Chemically there is a resemblance between the two compounds, though the free acid (mercaptobenzthiazole itself) is much more stable than xanthic acid. Both are readily oxidized, e.g., by iodine to disulphides, and can be estimated by iodometric titration. Qualitatively they are similar as collectors in flotation, although there are quantitative differences between them that may be important in practice. It is deduced that the influence of the nitrogen atom is subordinated to that of the sulphur atoms, and that the dominant group of these compounds is the mercapto group —SH or —5Na. The general method of investigation has been based on contact tests. Two temperatures, 10" and 35" C., have been chosen, and with a standard concentration of 20 mg. per liter of mercaptobenzthiazole (i.e., of the free acid) the influence of alkali, cyanide and copper sulphate on contact at sulphide mineral surfaces has been studied. This standard concentration corresponds to about 19 mg. per liter potassium ethyl xanthate; it brings out the differences between the minerals better than a higher concentra-

Jan 1, 1939

By Paul Weir

Bleaching clays have been used extensively in the oil-refining industries for a number of years. Their use in water purification is relatively recent and less extensive. They are frequently classified as (1) those naturally active and (2) those active after artificial activation with acid. Fuller's earths fall within the general group of bleaching clays and gradually the commercial term "fuller's earth" has been applied to natural clays originating, for the most part, in the southeastern section of the United States. Bentonitic clays are usually classed as activable and are prevalent in the southwestern section of the United States.l Bleaching clays vary considerably in chemical and physical properties throughout the country, or even in different parts of one deposit (Table 1). The fuller's earth type of clay is characterized by a lack of plasticity, relatively adsorbent, foliated structure, and does not swell to form a

Jan 1, 1942

By Thomas Robins

About six years ago the writer had occasion to visit a large magnetic iron-ore concentrating-plant, and then saw for the first time rubber belts employed for conveying-purposes. These belts were from 20 inches to 30 inches in width, and some of them were as long as 500 feet between centers. When I spoke of the enormous amount of material they handled with a small expenditure of power, the superintendent assented, but at the same time complained that although he bought the best quality of belts, the abrasion of the ore wore them out very rapidly, causing continually very large bills for repairs and renewals. On close examination several interesting points were discovered :

Jan 1, 1897

By Alden B. Greninger

THE time-honored description of the growth of metal crystals to form polycrystalline aggregates is. one in which two important steps are considered: (1) nucleation, and (2) dendritic growth, each dendrite starting from its individual nucleus and resulting (upon slow cooling, assuming no solid phase changes) in a macrograin. This picture of the process of crystallization is incomplete, and it is with the hope of enlarging upon it that the following summary and correlation of experimental results are given. MOSAIC STRUCTURE For an exact definition of the mosaic structure of metal crystals-if, indeed, one can be found that will hold for all metals-one must await the results of much experimental work in this field. The writer's investigations have been. confined almost entirely to copper and a few of its alloys. The following terms are proposed, and will be used in this report: Macromosaic Structure1.-Large-scale mosaic structure; more specifically, mosaic structure of a scale large enough to produce splitting of Laue spots on back-reflection Lane X-ray patterns2. The deviation from exact parallelism of neighboring macromosaics varies from a few

Jan 1, 1935

By Campbell Osborn

FROM the viewpoint of practical economic engineering the main value in studies of demand and supply lies in the information they give concerning the next movement of price. The title of this discussion is too comprehensive for detailed analysis and it will, therefore, be narrowed to the question of price measurement. The oil operator is interested primarily in net profits. Prices, costs and production determine them. Production is here used in its broadest sense. It includes refining and marketing. It is an operating problem. Prices and costs are economic considerations. Though costs are an important element of prices and profits, the subject is too large to be treated in a brief paper of this sort. In the long run, costs govern prices, but for the purpose of gaging prices in the immediate future the relationship of current demand and supply are more significant. Operating, expansion, retrenchment, sales and storage policies of oil companies are largely influenced by the feeling of executives concerning this relationship. The stockholders of companies whose executives are wrong may suffer. Investors who err in their judgment may likewise lose. On the other hand, oil companies and investors who appraise these factors correctly and move accordingly will profit. It is an important subject worthy of careful consideration.

Jan 1, 1928

THE Searles Lake orebody is located in the north- west corner of San Bernardino County. It is a dry lake bed with an exposed salt surface covering an area of 12 square miles. Recoverable mineral values are contained in the mother liquor below the surface of the lake. Stratification in the lake bed has separated the brine into two bodies which differ in composition. Although liquor is processed from both bodies, this paper will discuss only the upper structure brine. Fig. 1 illustrates a typical cross-section of the two commercial orebodies. The orebody is composed of a porous salt deposit 70 to 90 ft deep. The upper structure is separated from the lower orebody by a 12 to 16-ft thick impervious mud seam, as shown in Fig. 1. These salt structures are composed of 55 pct solid-phase salts and 45 pct voids which are filled with the original mother liquor.

Jan 2, 1954

By J. Walter Scott

IT is usual practice in the copper industry to use open horizontal molds for casting tough-pitch copper wire bars.1 A wire bar cast in this manner is partly characterized, by heavy wrinkles and a comparatively deep skin of oxide on the top of the bar, corresponding to the open side of the mold. On the theory that the rough, high-oxide surface might have an adverse effect on the rolling and drawing properties of a wire bar and might account for some of the irregularities of mill behavior, several bars which had been planed to remove the wrinkled surface were processed into wire. These bars responded to mill treatment more satisfactorily than did the regular wire bars. Realizing that machining the surface of one face of each bar would not be commercially feasible, it was decided that casting the metal into a vertical mold and cropping off the pouring end would accomplish. approximately the same result. Several wire bars of commercial size (250 lb.) were so cast and processed into wire for comparative test with bars cast in the usual horizontal molds. It is the purpose of this paper to present the results obtained from this investigation, in which commercial bar sizes and processing technique were used throughout. The results show that in general copper wire bars cast vertically are superior to those cast horizontally.

Jan 1, 1930

By U. Paakkinen, P. Eerola

In connection with theoretical studies of the dynamics and control of the flotation process, flotation cells and circuits at the Pyha- computer control of selective Cu - Zn - Fe sulfide flotation in the latter half of 1969. In this paper, the practical conclusions of these studies, conducted through simulation techniques, are summarized. The application of these results for control purposes implies a knowledge of the dependence of the flotation rate coefficients and the grade of concentrate on several factors, including aeration rate, froth depth, and reagent consumption. The relationships found in laboratory and plant scale tests are described. Off-line optimization studies, based on the relation- ships, are also described. The proposed steps in executing the computer control schedule are presented. In the first stage, a stabilizing control will be carried out using feed-back loops. A feed-forward control system which utilizes simple process models will also be tested. After these elementary stages, a proposed mathematical model of the circuit will be checked out and implemented with computer- run, plant-scale process tests. Off-line simulation will be continued in advance development of the control system. As a final step in the program optimal control of the process will be carried out through this model.

Jan 1, 1969

By E. G. Davis, G. V. Sullivan, J. P. Hansen

As part of its overall goal to maintain an adequate supply of minerals to meet national economic and strategic needs, the Bureau of Mines, U.S. Department of the Interior, investigated the feasibility of producing subsieve-size material by an attrition grinding method. The Bureau-patented technique employed intense agitation of a mixture of the material to be ground, a granular grinding media, and a suspending fluid. A variety of materials were successfully ground to extremely fine particle sizes. Studies were made to determine the method's efficiency in grinding industrial minerals and metals to minus 2 micrometers and ceramic powders to an average particle size of 500 angstroms. Transfer of this technology to a commercial scale has been achieved. Commercial-scale units are currently being used in the paper-coating clay and titania pigment industries.

Jan 1, 1980

By R. N. Singh, A. S. Atkins

One of the most difficult problems associated with modern mechanised longwall mining is the lack of system flexibility to deal with local changes in geology, seam thickness and the face design parameters. As a consequence of system rigidity and the quest for increasing the coal face performance, the percentage extraction in the U.K. is currently below 52%. The paper outlines the current guidelines used in face design which permit coal to be left in situ for various purposes and discusses the strata control implications in extracting subsequent panels in the same and adjacent coal seams. The paper examines the application of strata mechanics to the design of longwall layouts for maximizing .the percentage of coal extraction. Remedial measures include optimizing pillar dimensions, reduction in roof coal left for support purposes by improving the use of available powered support technology and application of thick seam mining methods including sub-level caving and techniques of extracting coal from odd shaped pillars. Case studies are described where coal extraction has been maximized by adopting a new single heading retreat mining system; a shallow seam partial extraction system utilizing, existing heading machines and minimisin8 coal sterilization in pillars by replacing longwall access roadways by goaf scour.

Jan 1, 1984

By R. H. Richards

In October, 1891,I read a paper before the Institute on a "A HandTelescope for Stadia-Work" (Bans., xx., 732), and promised to report at an early date some results showing the degree of accuracy attained with the instrument. I am now able to report on these results and also on certain improvements that I have made in the target since the first paper was read. I may say that I prefer the title, "Prismatic Stadia-Telescope," to that used in my earlier paper, for while the instrument can be used with perfect satisfaction for short sights up to, say, 300 to 600 feet when held in the hand, it is impossible to read milch longer distances without the use of a tripod, as a steady support for the instrument. Results are here given upon four combinations of prism and telescope. No. 1. A telescope made by Alvan Clark & Sons, 3-inch objective, 28 inches focal length, magnifying 60 diameters, the prism covering half the objective: Feet measured Reading of Distance reduced Reeding of rod pro by tape. the rod. to feet. portional to 100 ft. 127.66 1.1825 100 .92629 211.35 1.9585 100 .92666 326.59 3.0265 100 .92669 484.88 4.4925 100 ,92652 606.91 5.6225 100 .92641 Average,,92651 The value of this prism therefore is .92651 feet on the rod for 100 feet of distance, or 1 foot on the rod corresponds to 107.931 feet of distance. No. 2. A Bardou telescope having a 1-inch objective, magnifying 20 diameters, and a prism covering half the objective:

Jan 1, 1893

By R. B. Sudderth, C. R. Merigold

Greater, emphasis is being placed on recovering nickel from laterite ores by ammonia leaching techniques. New methods are required for lower cost, non-polluting techniques to separate more efficiently the metals of interest. Liquid ion exchange techniques meet these requirements with the added advantage of producing salable electrowon nickel cathodes at the plantsite. A complete solvent extraction- electrowinning process is described, including preliminary engineering and cost data for a typical plant producing 50 million pounds of nickel per year.

Jan 1, 1973

By B. L. Seegmiller

Horizontally stratified lithologies of certain open pit or strip mines create unique stability problems for mine operations. Such problems may result when specific lithologies, such as sandstone and shale, exist in final or long-term slopes. Slope instabilities may occur when a sandstone unit directly overlies a shale unit and ground water drains into the mine along the lithologic contact. In essence, the ground water erodes the underlying shales and undercuts the sandstone. Large sandstone blocks fail in a toppling mode and cause safety and cleanup problems. Use of rock reinforcement including chain link fencing, roof bolt mats, rock bolts, rock anchors, and shotcrete offers a possible solution to the problem.

Jan 1, 1985

By Linda P. Bono

Some mining engineers are pursuing their destinies in places far removed from what they might have envisioned back in the classroom. The path they follow to work each day may wind down Wall St., Park Avenue, LaSalle, or Market; their offices are in modern skyscrapers which offer all the amenities-air conditioning, thick carpets, attractive decor, and executive lunchrooms, to name just a few. The papers on their desks are a combination of financial figures and feasibility studies. But even in these surroundings there are indications of what these men do and where their professional interests lie-minerals are everywhere, from vast collections to one symbolic paperweight. . . there are sometimes specks of dirt under fingernails from a recent on-site inspection, belying the traditional banker's garb. . . and there are the wistful comments about finding it necessary to get out in the field.

Jan 9, 1978

By Homer E. Harris, William C. DeSieghardt, William A. Burgess

Under sponsorship of NIOSH, Eastern Associated Coal Corp., with the Harvard School of Public Health acting as a subcontractor, has determined for the first time the effective protection provided to working underground coal miners wearing approved half-mask dust respirators. This was done by conducting 187 man-shifts of in-mine testing in four different coal mines; included in this testing were 37 different test subjects representing 11 different job classifications and 5 different models of respirators. Presently available respirators on average provided significant protection levels to working miners even though on an intermittent use basis. However, "average" protection values were well below those achieved under laboratory conditions. Protection levels varied from man to man in a given work crew and from day to day for a given man. In addition, some of the factors affecting use and effectiveness of presently used respirators are discussed, as are areas in which improvements are needed, and the need to consider these improvements in context of a systems approach.

Jan 1, 1975

By D. M. Jamieson, M. P. Pearse, E. R. A. Plumstead

In 1948 the shaft sinking record in the Republic of South Africa was held by the Van Dyk Consolidated Mines Ltd. for a ventilation shaft with a footage of 461 ft sunk during the month of August 1941. This record remained for some ten years; but in the ensuing nine years it was broken no less than 13 times. Table I gives shaft sinking records throughout the world for the 21 years, 1940 to 1960. History shows that the wide, deep, timbered rectangular shaft had passed its peak of popularity by 1948, although it still had a great deal to commend it, both from the sinking and operational points of view. In sinking, it is easy to clean manually, and water can be handled by bailing when wet ground has to be negotiated; its shape also lends itself to equipping concurrently with sinking. In operation it provides the most convenient "in line" hoisting arrangement, and if the ventilation requirements so demand, it offers the simplest solution in that it can be divided into upcast and downcast sections. Furthermore, in the case of a multi-level mine, the shaft compartments can be reduced conveniently if the full area of the shaft is not required to serve all levels.

Jan 4, 1963

By D. R. Hanson

The acoustic vibrational spectra of impacted rock slabs were examined at the Denver Research Center, US Bureau of Mines, in an attempt to characterize the behavior of partially detached mine roof rocks. The ultimate goal of this study was to develop a technique or instrument that could provide a quick, accurate, quantifiable measure of mine roof stability. The power spectra of unstable rock slabs were found to contain more energy in the range of 200 to 1000 Hz than solid rock. Comparison of the power contained between 500 and 1000 Hz with that between 3000 and 3500 Hz provided a quantitative measure of rock stability. A lightweight prototype field instrument was designed, constructed, and field tested. This battery-powered instrument computes the power contained in the two frequency bands, compares their magnitude, and displays a number related to the stability of the block tested. Field tests showed the instrument provided reliable measurements of block stability even under conditions of noise that would have seriously degraded the accuracy of the standard methods of roof sounding.

Jan 1, 1986

By Ronald E. Versaw

Environmental legislation, both existing and proposed, requires that mills, tailings dams, evaporation ponds, and related processing facilities be located, constructed, and operated within stringent guidelines. An early step in planning a new processing facility is performing a site selection study in which topographic, hydrologic, geotechnical, and environmental parameters are evaluated for several alternate sites. Once a site is selected, then an environmental report, including a description of the proposed action, alternatives, baseline surveys, and discussions of potential environmental impacts, mitigation measures and monitoring programs is required. The federal legislation, siting studies, and environmental studies (along with the implications of these as they affect design) are discussed. In addition, costs for performing these studies and implementing control of effluents are discussed.

Jan 1, 1978

By Morris A. Dodd

The nodulizing process described converts finely divided zinc calcine into a dense purified nodule. These zinc nodules are suitable for direct use in zinc reduction furnaces, especially the horizontal retort type, for the production of metal or American process zinc oxide furnaces for producing lead free zinc oxide. The basic reactions are carried out in a rotary kiln fired with fuel oil or natural gas. The combustion gases travel countercurrent to the flow of the zinc bearing material. Volatile impurities are carried out of the kiln with the combustion gases and a small portion of the finely divided feed material. The gases are cooled and the larger solid particles are separated from the stream before the resultant fume is collected in a conventional cloth filter baghouse. The fume collected can be further processed by conventional wet processes for the recovery of metallic values such as lead and cadmium. In order to nodulize the calcine properly it is elevated to a point of incipient fusion. The agglomerated material falling from the kiln is cooled and then sized by passing through a screening and crushing system consisting of a jaw crusher and a roll crusher in closed circuit with a vibrating screen.

Jan 1, 1970