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By H. J. Modi, P. L. De Bruyn

In recent years interest has been aroused in flotation rate studies both from a technical and a more practical aspect. With increasing fineness of grind becoming a necessity in treatment of low grade ores, differences in flotation rates of various size ranges will assume importance in the evaluation of overall recovery results. Theoretical analysis of flotation kinetics was initiated by Schuhmann, who sought to define flotation rate of a given mineral and specified size range in terms of certain physical variables of the flotation system. Using as a basis for his analysis the bubble- particle encounter hypothesis previously advanced by Gaudin, Schuhmann writes for the rate of flotation (R,) of particles of average size x, [ ]

Apr 1, 1956

By James L. Calver

Fuller’s earth is an inexact term applied to certain clays that have a marked ability to adsorb coloring materials from animal, vegetable, and mineral oils. Many clays have this adsorbing power to a slight or very limited degree, and certain other clays, chiefly bentonites, as well as minerals such as bauxite, can be made highly adsorbent by activation with acids or alkalies, but the term fuller's earth is generally reserved for clays that are naturally highly adsorptive. In most fuller's earths and practically all activable clays montmorillonite is a dominant mineral. No definite clay mineral or group is implied in the name fuller's earth, and the distinction between fuller's earth and other clays that have more or less bleaching power is not sharply drawn. The name as generally used has no genetic or mineralogical significance. The fuller's earth produced in the Florida-Georgia district contains the clay mineral attapulgite. This mineral name was first used in 1930 by DeLapparent to apply to a hydrous aluminum magnesium silicate found in the fuller's earth from Attapulgus, Ga., and Quincy, Fla. An essential component of its structure, determined by Bradley in 1940, is that the silica chains of the molecule are arranged similarly to those of the amphibole minerals. The fibrous nature of the lath-like crystals of attapulgite is apparent under magnifications reached by the electron microscope. The ideal formula, [(OH,), (OH), Mg, Si, 0,-4H,O], contains no aluminum, but there is considerable replacement of the magnesium by aluminum. In the classification of clay minerals, attapulgite is associated with sepiolite and polygorskite rather than with mont-morillonite.

Apr 1, 1956

By Harold E. Rowen

Sintering is accomplished at a temperature of more than 2000°F. For the purpose of this discussion it will be defined as the art of burning a solid fuel with 90 to 95 pct ash content. Think of the problems of combustion involved in keeping a home furnace burning properly with 12 to 20 pct ash in the fuel and remember that the amount of fuel involved in the 5 to 10 pct combustion loss represented by the definition has to be just about right or nothing is going to happen. Our forefathers discovered that many ores containing metals csscntial to the steadily rising standards of living were associated with other minerals, sulfur and arsenic, for example, which had to be removed before ultimate refining. They did this by utilizing the solid fuels they had available-the sulfur or other readily combustible components- to create roasting heat.

Apr 1, 1956

By William B. Plank

Mineral engineering student enrollment in U. S. and Canadian schools for 1955-1956 is 11,408, an increase of 11 pct more than last year. The undergraduate and graduate engineering students in both countries number 251,765, or 13 pct more than last year. These figures have been released by the American Society for Engineering Education. The largest increase in the undergraduate mineral engineering group in the U. S. is in ceramic engineering, with 676 students, or 31 pct more than last year. The next largest increase is in mining which shows a gain of 13.5 pct, compared with a gain of 13.1 pct in the total undergraduate enrollment in all engineering schools approved by the Engineers' Council for Professional Development. This figure is 190,355, which approaches the prewar figure. Metallurgical undergraduates increased 13 pct; geological, 5 pct; and petroleum, 2.5 pct. This year the figures for geophysics are combined with those for geological engineering, making a total of 1610 undergraduates, of which the geophysicists comprise about one seventh.

Apr 1, 1956

By James J. Norton, Lincoln R. Page

Effective methods for determining grade and reserves of pegmatites in advance of mining have been developed in recent years. When intensive work began on the economic geology of pegmatites during the early years of World War II, it was widely believed that grade and reserves could be estimated only in a most general way. The literature indicated that not all pegmatite deposits are unpredictable, but statements emphasizing unpredictability and irregularity seem to have been more widely accepted. Many standard references reflect the prevailing opinion that minerals are unsystematic in their occurrence in pegmatites. Pegmatites have been de- scribed as "notorious for their irregular structure," and minerals within pegmatites as "irregularly distributed," "irregularly disseminated,'' of "erratic occurrence," "proverbially erratic in distribution," "characterized by extreme irregularity in size and distribution of the essential minerals, and variety and proportion of the accessory minerals, and "spotty."

Apr 1, 1956

By H. H. Waller, C. H. Brehaut

At the Jeffrey mine of Canadian Johns-Manville Co. in Asbestos, Que., automatic batched concrete from surface is placed underground pneumatically for distances of 2500 ft directly into forms or to a second placer for greater distances, through 6-in. pipe of high carbon steel. The use of Celite C-4-C in addition to the usual aggregates achieves greater compressive strengths, lowers cost, reduces segregation, and improves workability and placeability results. Each year 25,000 cu yd of concrete are placed without interrupting production and development work in the mine, making possible a cheaper concrete that can be poured wherever and whenever it is needed. In about 90 pct of the underground openings in the Jeffrey mine concrete is necessary to preserve them in their original sizes and shapes for production. In the remaining 5 pct, the greater portion is united with or without steel support. When large quantities of concrete were forecast for underground use at the Jeffrey mine, preliminary and first hand information regarding pneumatic placing was acquired from articles by Bernhardt and Swanson and visits to their respective mines.

Apr 1, 1956

By Jerrold Marcus

The peninsula is roughly 700 miles long and 180 miles wide. The southern portion is the American-sponsored Republic of Korea and the northern half is the Soviet-promulgated People's Democratic Republic of Korea. The area of South Korea is almost 40,000 sq miles, about the size of the state of Maine, and contains a population estimated at 22.5 million. Prior to annexation by Japan in 1910, the Korean economy was based on a system of self-sufficient farming units, but with Japanese occupation it was geared to Japanese economy. Emphasis was placed on supplying raw materials for Japanese industry and food surpluses to help feed Japan, and on providing a connecting link with Manchuria, traditionally a major raw material source for Japan. Small metal refineries, ore processing, and semi-finished goods manufacturing units grew into existence in the northern part of Korea, where much of the electric power is generated. Under Japanese domination, the south remained essentially agricultural. Food productivity was increased, although manufacture of elementary consumer goods was stimulated for Japanese markets.

Apr 1, 1956

By L. A. Wright, J. F. Emerson

The Pine Creek mine, owned by Union Carbide Nuclear Co., Div. of Union Carbide and Carbon Corp., is one of the world's largest producers of tungsten. The mine is located on the eastern slope of the Sierra Nevada Mountains, about 25 miles north- west of Bishop, Calif. Prior to 1948, production from the property came either from surface pits or from underground workings above A level haulage tunnel. The tunnel is at an elevation of 10,900 ft, which left 500 to 600 ft of vertical backs to the surface outcrops. Heavy production demands during World War II hastened the planning for long range development of orebodies below A level. A 7000-ft haulage tunnel, 1500 ft below A level, was started in 1943 and completed in early 1947. This haulage tunnel is at an elevation of 9400 ft and is known as Zero tunnel.

Apr 1, 1956

By J. L. Gillson

The big mass of anorthosite in the Lake Sanford district and the bodies of titaniferous magnetite that occur in a small area near the south margin of the mass have been described repeatedly, and the puzzling problems of the genesis of the rocks and ores have stimulated the deductive reasoning of geologists for a hundred years. Some of these men have taken a leading part in describing the anorthosite rock and forming hypotheses concerning its origin; some have contributed most to the study of the ore deposits; and some have made classical Studies introducing a basic approach to the problems of the anorthosite rock and genesis of the titaniferous magnetites. Much of the writing on the problems of rock and ore genesis has been based on physical-chemical reasoning rather than on field and microscope observations of the rocks and ores. Most of these geologists conclude that the anorthosite was formed by true magmatic crystallization, involving previous settling or squeezing out of ferromagnesian minerals from the parent magma. The associated gabbro is a separate segregation or later intrusion, and the lighter colored and finer grained facies of the anorthosite is either a chilled border zone of the anorthosite or the result of granulation by crushing of the coarse, dark blue rock of the main mass. This blue rock, called the Marcy type, is named after the highest peak in the range. The finer grained and lighter colored rock is called the Whiteface, after another mountain appropriately named for a cliff colored by this facies of the anorthosite.

Mar 1, 1956

By Juan Ayza

En este último artículo se describe el sistema de IMPINGER - como parte del muestreo y así determinar la cantidad de polvo adherido. Dicho sistema produce una presión negativa sobre el agua de un tubo, y es donde la presión atmosférica introduce el aire por un tubo central, cuya boquija está debajo del agua y a 5 mm. del fondo. En ese sentido, la mayor cantidad polvo queda en suspensión. De otro lado, se describe el método cualitativo cinematográfico donde se percibe la cantidad de polvo a través de la captación de luz fotográfica, aunque el problema es el avaluúo preciso de la sílice li-bre en el rango de polvo respirable.

Mar 1, 1956

By M. C. Fuerstenau, D. W. Fuerstenau

Long-Chained aliphatic amine salts have been used for the separation of sylvite (KC1) from halite (NaC1) by flotation. It is puzzling how these two minerals, which are so similar chemically and crystallographically, can be separated by this method. Gaudin as postulated that the difference in floatability of halite and sylvite with salts of primary amines depends on ionic size: In the case of amine flotation, the cation would attach itself to the chloride. I have a speculation there, which I cannot prove, that the ammonium group, that is the –NH3 group in the amine, floats potassium chloride because the dimensions of this group as it has been measured in other compounds is almost identically the dimensions of the potassium ion, quite different from the sodium ion, and so it fits where potassium had been, in place of it and not attached to it.

Mar 1, 1956

By Kenneth N. McLeod, Donald W. McGlashan

In the use of free bubbles with precise temperature control and continuous pH measurement, the contact angle apparatus differs from all previous equipment. Experimental procedures differ sharply from the captive bubble method of introducing the gaseous phase in the three-phase system. When freed from the tube and captured by a solid surface, a bubble more closely conforms to the spherical ideal set up by the usual mathematical analysis of surface free energy or surface tensional relationships of the forces involved. The assembled equipment, Fig. 1, departs from the usual contact angle apparatus in providing: 1) water circulation for fixing temperature, 2) instruments to measure and record pH during testing, and 3) a system for producing and using free bubbles. The apparatus allows testing over a broad range of closely controlled conditions, and the use of free bubbles gives contact angles independent of operator manipulation, which was unavoidable in the older captive bubble method. A bubble released below the specimen rises through the liquid and contacts the mineral. If the mineral is gas-avid the bubble adheres, developing a finite contact angle.

Mar 1, 1956

By William Allen

For the past six years gravity surveys have been used for underground prospecting in the copper mines at Bisbee, Ariz. The primary purpose of the surveys has been to reduce the diamond drilling and crosscutting necessary for exploration. Since many of the orebodies are small, and geologic control is not always apparent, any information that will direct the drilling and crosscutting is highly desirable. Because of extensive development and exploration work in the copper mines at Bisbee, it has been possible to cover more than 630,000 ft of crosscuts on 30 levels with the gravity surveys. In the process the gravity procedures have been refined to a high degree.

Mar 1, 1956

By S. A. Braley

Drainage of acid mine water into surface streams of coal mining areas is one of the most serious problems of stream pollution, since there is no known method that completely prevents its forming and no economically feasible treatment after it has formed. The mine acid problem differs from other pollution hazards because acid production does not end with cessation of mining but actually becomes more evident when pumping is stopped. The acid problem in the Pennsylvania, Ohio, West Virginia, and Kentucky bituminous coal areas of the U. S. began with the first operation in 1761, and the volume of acid discharge today is largely the cumulative result of years of mining. Provided they lie above the drainage area, the oldest mines, now long abandoned, are almost without exception producing acid in the same manner as those now operating or recently abandoned.

Mar 1, 1956

By W. A. Boyer

Mine hoisting ropes can be loaded to capacity only when the strength of each component is exactly known. Characteristic curves provide this information. When load and rate of acceleration are specified for an individual rope, the characteristic curve assumes a predetermined shape. The factor of safety is the value derived by dividing the breaking strength of the rope by the total stress on the rope where it goes over the sheave wheel. Total stress is made up of the weight of skip and cage, weight of ore, weight of rope between sheave and rope clevise or attachment, friction load, and acceleration force. Bending stresses are neglected in this discussion, as sheaves and drum diameters are assumed to be large enough to reduce these stresses to a negligible value.

Mar 1, 1956

By Robert T. Walker

Robert T. Walker and Woodville J. Walker (Walker Engineering Corp., Salt Lake City)-Mr. Kinkel's article embodies, in condensed form, the results of the first detailed and complete geological survey that has ever been made of the long neglected but potentially very important West Shasta Copper-Zinc district, in Shasta County, California. In view of the difficulties of the terrain and the complexity of the geological structure, this represents a notable achievement, and it is with regret, therefore, that the writers find it necessary to differ from Mr. Kinkel's conclusions on two important points. The first has to do with the interpretation of two members of the stratigraphic column of formations in the district; for purposes of comparison, the description of these two members according to Mr. Kinkel is shown parallel to the description of these members according to the writers, see Fig. 14, Mr. Kinkel's nomenclature being used

Mar 1, 1956

By N. H. Parker, J. G. Papailias, G. Gutzeit

In its many forms, the turbine has greater latitude of application than any other mixing device. It is readily adaptable to all tank shapes, from the shallow pan to the tall and narrow stovepipe. Although turbine mixers can be adapted to most tank conformations, experience has shown that there is a preferred shape for optimum efficiency in each service. In the accompanying drawings this relationship is illustrated by the shallower tank for slurry suspension. The taller tank is preferable for continuous staged systems, or maximum retention of the gas phase in absorption. No single turbine covers the entire range of these applications with maximum efficiency. The back-sloped blade offers maximum power economy. The straight blade develops a higher discharge velocity for the dispersion type of service requiring localized shear. The same high shear environment is provided by the back-sloped impeller with stator ring assembly, which permits the most positive discharge control, Fig. 1. Positive stream control is critical in solids suspensions.

Mar 1, 1956

By Edwin B. Douglas

The Blackbird mine is owned by Calera Mining Co., subsidiary of Howe Sound Co. The mine is located in the Salmon National Forest, Lemhi County, Idaho, about 22 miles west of Salmon and 220 miles north of Pocatello. The thought of producing cobalt from a prospect that offered excellent opportunities stimulated everyone connected with this project. But as time went on, it was found that every phase of the development presented unusual difficulties.

Mar 1, 1956

By Nelson Severinghaus

Consolidated Quarries Corp. must conduct operations for an average sales price of $1.25 per ton, about the same price at which stone was sold 25 years ago when the dollar was worth twice what it is now. To maintain success in a competitive business, the company must solve the usual production problems, which will be discussed here in the order they occur in the flowsheet. Most crushed stone quarries must first remove soil and decomposed rock. Although seasons of lower sales sometimes release regular quarry excavating and haulage equipment for this purpose, overburden is often too extensive for this method to be used. In such cases, special equipment must be assigned or the job may be contracted. As many earthmoving contractors have heavy duty specialized equipment well suited to overburden removal, they should be seriously considered before the job is undertaken. Pockets of clay beneath peaks of hard stone sometimes defy mechanized removal. Pick and shovel laborers at this point might be supplanted by more ingenious use of pumps and water or some other mechanical means. Where overburden is extremely heavy or difficult to remove, underground mining must be considered.

Mar 1, 1956

By Joseph J. Yancik, Leonard L. Felts, George B. Clark

Little information has been published concerning the actual or useful amount of energy obtained from explosives when they are used for blasting. To provide more data on this subject, 8-in. neet cement cubes were blasted in a steel plate box and the breakage energy evaluated by comparison with drop crusher results using Rittinger's," ' Kick's,%nd Bond's' theories. Theories by Bond and Wang," Lineau,' Hatch,' Roller," and others were not considered applicable. Those used in this investigation may be expressed mathematically as follows: [ ] The above equations were employed to determine values of KK, K for particle size distributions similar to those obtained from the blasting curves. These values were in turn used as a means of approximating the specific energy of the blasted material. The efficiency of crushing by blasting was then determined by dividing this specific energy by the maximum available work of the explosive per gram of cement.

Mar 1, 1956