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By N. Mohan, A. K. Biswas, V. Y. Sampat Kumar

At low sodium-oleate concentration, calcite flotation is substantially improved by the use of CO2 instead of air. Electrophoretic mobility measurements indicate that carbonation results in the accumulation o f positive charge on the calcite particles. This heightens adsorption of oleate anion, an effect confirmed by tracer-technique measurements. Fundamental insight is obtained as to how CO2 serves better as an activator than some mineral and organic acids, how oxalic acid acts as a depressor, and why the influence of Ca++ ions, liberated during carbonation, on flotation behavior of calcite is insignificant and sometimes adverse.

Jan 1, 1972

PASSING over the derivation of the word as well as the description of the alum that has been written of as a liquid and that was once called natta, I tell you that the alum that is commonly called rock alum today is a congealed earthy substance, clear and transparent, of a hot and dry nature, and of a bitter taste with a certain unctuous saltiness. It has an astringent and corrosive property and is drawn from mineral stones by means of art. All that I have seen is of the same nature but of two colors,

Jan 1, 1942

By Daniel T. O’Brian

Exploration targets and results in the mining industry are commonly summarized in terms of tonnage and grade. Business appraisals require, as additional information, the expected profit or loss implied by the physical summary. The early incorporation of knowledge gained through financial analysis computations can provide a means for economically resolving many common exploration and development problems. Examples of such applications from the activities of exploration planning, reconnaissance, land acquisition and develoment planning follow. While prospecting for mineral deposits, geologists are frequently asked what they have found or hope to find. The response is usually descriptive, such as: "50 million tons of 1% copper," and the economic implications are deferred until a capital investment decision is required. At that time a financial analysis integrating the four analysis components-tonnage and average grade above cutoff grade, capital and operating costs, product value, appropriate profit or loss accounting-are completed.

Jan 10, 1969

By Daniel C. McLean

Copper concentrates produced by many operations in the United States and South America contain chalcocite (79.9% Cu) as a major component, yet the grades of these concentrates rarely exceed 25 to 28% Cu. Mineralogical studies made by E.P. Cadwell indicated that the low grades were caused by dilution by pyrite rimmed with secondary chalcocite. Laboratory and plant tests proved that concentrates could be significantly upgraded by using a simple, low cost cyanide leaching technique to dissolve the rims and reject the pyrite. The many advantages of this new procedure are cited and the process steps and a typical flowsheet are described.

Jan 1, 1984

By D. F. Kelsall

During the past twenty years, and especially in the last decade, hydraulic cyclones have found increasing application in metallurgical processing as classifiers and, under special circumstances, as thickeners. To a more limited extent cyclones have been used to extend heavy, or dense, medium separation into the finer size ranges, and several attempts have been made to separate dispersions of immiscible liquids with a view to use in the field of liquid- liquid extraction. Before considering several aspects of conventional application, less conventional applications and some potential uses of modified cyclones, the mechanism of separation within a cyclone and the effect of the, major variables will he summarized.

Jan 10, 1963

Jan 1, 1931

By R. Hogg

The mathematical description of solids transport in mills is an important aspect of the development of comprehensive models for the analysis, simulation and control of grinding systems. The basic mechanisms of particle transport and mixing, including gravity flow, carrier fluid transport, and "diffusion", are reviewed and their relative importance in wet and dry ball mills is discussed. Specific models for transport and mixing in dry, grate-discharge and wet, overflow ball mills are described. The limitations of the models, parameter estimation problems, scale-up criteria etc. are discussed and the conditions which lead to particle size dependent transport, and hence to internal classification in the mill, are described in detail.

Jan 1, 1984

By Roger K. Clifford, Gary W. Hudiburgh

The amine flotation of feldspar from a magnetite concentrate produced at a domestic concentrator was investigated using zeta potential measurements, Hallimond tube flotation tests, and laboratory-scale flotation tests. The point of zero charge of six feldspars (microcline, orthoclase, albite, anorthite, anorthoclase, and oligoclase) range from pH 1.4 to 2.5. Hallimond tube flotation tests using amine flotation reagents were performed on these feldspars and on gangue material (quartz, albite, and microcline) from the magnetite concentrating plant. Laboratory-scale (623 g and 2500 g) flotation tests were performed on the magnetite concentrate to float the feldspar. The effects of three different collectors, two levels of collector concentration, three pH levels, starch, HF acid and regrind were investigated.

Jan 1, 1977

By Robert S. Shoemaker

Recently we read a short article which stated that Marcona Corp. was studying the use of 25,000-hp autogenous grinding mills for an iron ore project in Alaska. As if that weren't enough, they were going to dispense with the primary crusher and feed run-of-mine ore to the grinding mills which were to be driven by wrap-around seven-cycle motors. We see also that Bougainville Copper Co. will be grinding 90,000 tpd of ore in only eight 4250- hp ball mills. At Bougainville too, their float section will be the first large one to be completely equipped with the new 350-cu ft flotation cells. After a half century of relatively peaceful growth in the minerals industry, we are now seeing almost exponential advances in both equipment and plant size. At the same time, we are seeing a constant blending of hydro and pyrometallurgical techniques and processes into minerals beneficiation until the sample grind-'em-up-and-concentrate-'em plant is becoming a rarity.

Jan 1, 1970

By Charles M. Rolker

The mining industry of Colorado received a powerful impetus from the enterprising railroad builders who, rating highly—perhaps, in some instances, too highly,—the natural resources and favorable conditions of the State for the production of the precious metals and lead, covered it, in advance of any thorough general development of these resources, with a network of railroads. At that time, everything was viewed couleur de rose; population was gaining rapidly, and much more in the way of productivity was expected of certain districts than was subsequently realized. It is, therefore, not quite fair to judge of the wisdom of constructing some of the branches of the Colorado railroad system from the standpoint of later experience. With the building of railroads, a demand sprang up for iron and

Jan 1, 1886

By Charles R. Holmes

MORE than 70 igneous pipes and dikes are known to occur in Cambrian sediments throughout an approximately circular area of about 75 sq miles, in southwestern Ste. Genevieve County and southeastern St. Francois County, Mo., across the southern portion of the Farmington anticline, which is outlined in fig. 1. From evidence obtained from fossil fragments taken from some of the intrusives, and from the similarity in composition of the more basic intrusives to those of known age in surrounding states, these pipes and dikes are believed to be at least post-Devonian and probably Cretaceous in age. As first postulated by Rust[1], these intrusives are believed to represent explosion tubes, or diatremes, punched through great thicknesses of solid rock by gaseous pressure.

Jan 11, 1950

By Andrew Allan

The Thompson Creek Coal & Coke Corp. operates three coal mines which presently supply the United States Steel Corp. with high grade, medium volatile coking coal at a rate of 1000 tpd. Mining is done at an elevation of 8000 ft, approximately 13 miles southwest of the small town of Carbondale, Colo. The coal is cleaned mechanically by heavy media and Deister tables, after which it is trans- ported to the railhead at Carbondale. GENERAL GEOLOGY The coal beds in this area lie in the Mesa Verde formation of Cretaceous age. Three beds are now being mined, with a fourth possibility pending further exploratory work. Formation of the Rocky Mountains tilted the sedimentary strata approximately 30º and created considerable faulting throughout. These faults, which range from a few inches to 35- ft displacement, constitute serious obstacles to mining.

Jan 4, 1966

Two sessions during the recent AMC Mining Convention in Los Angeles, September 23-26, served to update industry personnel on the status of health and safety regulations in the US. As reflected by the American Mining Congress resolution on mine safety and health, "Based on experience with the federal Coal Mine Health and Safety Act of 1969 and the federal Mine Safety and Health Act of 1977, (AMC) does not believe that laws designed to force compliance with regulations through the imposition of criminal or civil penalties will result in safer mines. (AMC) feels that the government's participation will be much more productive if greater emphasis is placed on research, training, and inspections aimed primarily at assisting operators and employees in recognizing and eliminating hazardous conditions and practices.

Jan 11, 1979

By S. R. Gilbert, B. W. Burdett, L. B. Hales

A brief review of grinding control systems is given with a review of the most popularly reported control loops. The trend toward more sophisticated control systems in terms of control strategies and control equipment is discussed, and the reasons for the popularity of distributed control equipment are outlined. The evolution of the interface between the operator and the process and its importance in plant control is described. Finally, the authors' view is given as to the future of grinding control.

Jan 1, 1984

By C. A. Wert, K. C. Hsieh

Mineral particles in coal have enormous variation in size. Some are large enough to be seen by eye, others can be seen with the optical microscope and still others are so small that they can be resolved only by electron microscopy. We paid particular attention to particles of clays and sulfides less than 1 pm in size. This paper describes typical minerals and reports on the application of the techniques of electron microscopy to coal.

Jan 1, 1984

By Weldon B. Smith

When faced with excavating vast amounts of overburden at its surface coal mining operation in Centralia, Wash., the Washington Irrigation and Development Co. (Widco) chose to utilize a bucket wheel excavator and shiftable conveyor system. In the early 1970s, Widco-a subsidiary of the Washington Water Power Co.-held reserves of sub-bituminous C coal estimated at some 180 million tons (200 million st). Subsequent investigation of the overlying land formations revealed the need to excavate millions of bank cubic yards of material as part of the mining plans.

Jan 7, 1979

By R. W. Jenkins, O. J. Neslage

The need for mechanized drilling to decrease mining costs has resulted in the development of the jumbo from column-and-bar drill by carriages to hydraulically controlled jib jumbos. Resultant savings from use of improved jumbos have been high enough usually to retire the machinery investment within a year. The jib jumbo unit has been and applied successfully to development and preparation programs and flat-bedded stopes, and an even wider field is forecast for its use.

Jan 5, 1950

By Willard Ide Pierce

The Department (formerly called State) of Tolima, which is beginning to attract considerable attention in this country on account of its mineral wealth, comprises an area of 18,415 square miles, lying between latitude 1" 34' 25" and 5" 44' 12/" N. and between longitude 74" 25' 45" and 76" 34, 25" W. from Greenwich. It is bounded on the north by the Department of Antioquia, on the east by the Departments of Cundinnmarca and Cauca, and on the south and west by the Department of Cauca. It is the most recently created of the States of Colombia, having been established by decree of April 12th, 1861, and being composed of the old provinces of Mariquita and Neiva, and of the districts Melgar, Carmen, Cunday and Santa Rosa, of Tequendama.

Jan 1, 1888

By Norman Weiss

There was a time in the early history of man's use of metals when ore could be directly reduced to usable form by the use of fire. In those days the term "milling," or its many synonyms signifying the concentration of an ore's metallic con- tents before smelting, was little known. Centuries later, even before Agricola, or even before the Greek and Roman civilizations, simple means were found to concentrate metallic minerals that possessed special characteristics such as high specific gravity, hardness, magnetic response, or simple appearance. In this way, the art of milling became valuable to civilization because it eliminated most of the cost and labor of transporting and melting the worthless nonmetallic part of an ore. As civilization became more dependent upon metals and solid fuels, the art of ore dressing (one of our synonyms) increased in importance and complexity, until today it has become a gigantic industry firmly based upon a mature but rapidly advancing technology. Technically trained people are needed in growing numbers to serve this industry.

Jan 1, 1970

By C. G. Albert

The literature of paper technology contains a number of articles having reference to developments in the field of coating and filler clays for use in paper manufacture. Much of this information has not been included in mining publications and has therefore not been readily available to all in the mineral industry. Recent developments in this field, including spray drying of clays, are presented here. U. S. Bureau of Mines figures for 1952 indicate that the paper industry consumes more than 50 pct of all kaolin produced and sold in the U. S. As most of the kaolin used by the industry comes from Georgia producers, the fraction of their output destined for paper use is thus appreciably higher than 50 pct. Small wonder that the kaolin industry, especially in Georgia, is highly sensitive to the quality requirements of paper mills and must respond promptly to technological developments in paper manufacturing.

Oct 1, 1955