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By John F. Sulzbach, Donald K. Walker, John F. Abel

With the increasing military significance of the arctic, the U.S. Army Corps of Engineers' ice- tunneling research program has been instituted to determine the feasibility of excavating large under- ice openings. Such openings would provide for year- around storage of material and housing of personnel, independent of surface weather conditions. This unique ice mining operation has been carried on in the tunnels at Camp Tuto, Greenland, during the summers of 1955, 1956, 1957 and 1958 by the U.S. Army Snow, Ice, and Permafrost Research Establishment (USA SIPRE), Wilmette, Ill. Supervisory personnel for the tunneling projects principally have been civilian mining engineers and mining engineering students from Colorado School of Mines. They have been employed under contract between USA SIPRE and the Denver Research Institute (DRI) of the University of Denver, Denver, Colo. Laborers have been enlisted military personnel attached to the U.S. Army Polar Research & Development Center (USA PR&DC) , Ft. Belvoir, Va.

Jan 6, 1959

By Bunting S. Crocker

Pebble grinding was used at Lake Shore Mines in 1949. A full description of experimental evidence and test plant results was published in 1952 1 and further operating details in 1954.2 In more recent years the term autogenous grinding has been coined and is now frequently seen in the technical literature. Autogenous crushing and/or grinding covers any grinding mill in which the larger of ore are made to grind the fine pieces; the crushing and grinding may be either dry or wet. This discussion deals only with wet autogenous grinding, and only in the fine grinding part of the circuit, i.e., from 6 mesh to 92 pct -325 mesh. The term pebble milling could apply to fine autogenous grinding in which the pebbles are made from the ore itself, or it could also refer to grinding with pebbles, such as flint pebbles, from a source outside the mine.

Jan 5, 1959

By R. F. Sheldon

Largest uranium deposit in the Northwest is Dawn Mining Co.'s Midnite mine on the Spokane Indian B Reservation. The orebodies lie along the contact of granite and metamorphosed sedimentary rock and are controlled by faults and shear zones near the granite contact. In the oxidized zone the deposits consist mainly of the secondary uranium mineral meta-autunite; sooty uraninite and primary uranium minerals are known to occur at greater depths. Elevations in the mine area range from 2500 to 3500 ft. The rolling hills and low, rounded mountains are covered with grass and evergreen trees.

Jan 5, 1959

By J. E. Lawver, G. L. Samsel

The success of many mineral dressing processes, including froth flotation and electrical concentration, depends largely on knowledge of physical and chemical structures of the mineral surfaces involved. As a general rule solids have surface layers, usually invisible by optical tests, that differ from the substratum. To the mineral engineer, therefore, a knowledge of the surface structures of minerals is of paramount importance. During the past decade one of the most powerful tools in the study of froth flotation mechanisms has been the use of radioactive tracers, but this technique usually cannot give definite information regarding the chemical changes that may or may not have occurred at the surface.

Jan 5, 1959

By Otto Rellensmann, Eugene P. Pfleider

For many years mine surveyors and exploration engineers have sought an accurate means of transferring meridian underground by using the gyro-compass. These efforts have generally failed, either because they were inaccurate or because the size and cost of the unit were prohibitive. During the past ten years, however, great strides have been made. Autonetics in California has developed a comparatively light-weight (100-lb) gyro-theodolite, and the Institute for Mine Surveying at Clausthal Mining Academy in Germany has developed an instrument that is accurate to within 20" to 30" of arc. Concurrently, Minneapolis-Honeywell has produced an astounding gyro, the size of a salt shaker, that weighs less than 0.5 lb and compares favorably in performance with the 50-lb gyros of conventional design. This unit, designed for missile guidance, should be adaptable for surveying small boreholes. Given the proper interest and approach from the engineering fraternity, excellent gyro- compasses could probably be available for accurate underground survey work at nominal cost within the next three years. Principles of the Gyro-Compass: The gyro- compass, used for 50 years as a navigational instrument in ships and aircraft, senses the turning axis of the earth and points out true polar north. It does this by employing the earth's rotation, the force of gravity, and the precession characteristics of a gyro. For further details the reader is referred to several excellent publications1-3 covering the principles and application of the gyroscope.

Jan 5, 1959

By A. Tremari, Paul I. Eimon

Photogrammetrists are studying with new interest the problems of mine mapping and mining engineers are beginning to see what photogrammetry can do for them. Administrators in a number of European and U. S. mines have tried photogram- metric methods and are finding that better maps and data, needed for mine development, can be produced with savings of time, men, and money. In addition to wide use in small scale mapping projects, photogrammetric methods are now used for producing large scale plans and maps in German coal and lignite mines, in some U. S. open pit mines, to inventory TVA coal stock piles, and to compute highway excavation volumes. In each case surveying and map compilation has been made more efficient and accurate by photogrammetry and at significant savings over ground methods.

Jan 5, 1959

By R. S. Archibald

The subject of this paper is particularly appropriate, since Daniel C. Jackling was active in early exploitation of taconites on the Mesabi Range and contributed greatly to their later economic development. After his success in developing the low grade porphyries in the West he looked for more worlds to conquer, and so undertook the concentration of low grade taconites, from which he hoped to produce commercial ore. Mesabi Iron Co., organized in 1919, actually did produce merchantable sinter from taconites in 1922. The enterprise did not prove commercial at the time, as cost of production was high and the surplus of iron ore in the Lake Superior District already contributed to a low market price, but this same property has since been developed by Reserve Mining Co. The work done by Jackling had much to do with the success of this later venture. Iron ore was first discovered on the Marquette Range in Michigan in 1845. The first ore from this range came from the old Jackson mine in Negaunee in 1848. During these early years this property and others on the Marquette produced limited tonnages for transportation to Lower Lakes and for consumption by charcoal furnaces in the area, where a plentiful supply of hardwoods furnished the charcoal for iron smelting. The Marquette and other ranges tributary to Lake Superior did not produce much ore for transportation to Lower Lakes until the locks at Sault Ste. Marie were constructed, but from the time the first lock at the "Soo" was completed in 1855 these ores were transported through the locks to consumer centers in the East. The Marquette Range has a history of continuous production from 1848 to the present day.

Jan 5, 1959

By Armand Bur, W. R. Reichenstein

Since coal is one of the largest cost items in the production of electricity, its analysis for heat value and composition has been the subject of intensive study. Sampling started with crude hand methods, out of the railroad car or barge or from moving conveyor discharge, and progressed to reliable mechanical in-plant sampling systems. The mechanical system takes its sample from a falling stream of coal such as a conveyor discharge or crusher discharge hopper. But this has a disadvantage in that the identity of the coal is lost. Coal is shipped to the user in train-loads, often made up of shipments from various mines. When the cars are dumped into hoppers and the coal conveyed to the power station, the various shipments become mixed because residual coal remains in hoppers and chutes.

Jan 5, 1959

By Frank M. Stephens, Robert D. Macdonald

As processes for handling low-grade or complex ores become more complicated and as new methods are found, the need arises for more complete and detailed pilot-plant studies to protect the capital investment required for a full-scale plant. Occasionally a process is firm technically, but there is a need for a demonstration plant that will convince nontechnical men of the wisdom of investing in a full-scale operation.

Jan 5, 1959

By Howard S. Strouth

Investors and mining companies in the U. S. have recently shown increased interest in the Union of South Africa. This has been sparked partially by the founding in the U. S. of a large investment trust which will hold substantial shares in many of the leading gold and uranium producers. The average U. S, mining man's judgment of the Union, however, may be somewhat clouded by recent headline news. We are inclined to take a strong dislike to the stern measures of the present Union government with regard to its native majority. Others possibly think of South Africa in krms of a British colony which, under pressure of rising African nationalism, must eventually be abandoned. These concepts frequently suffer for lack of precise information.

Jan 5, 1959

By B. H. Bergstrom

In reading this article, it was difficult to follow through the example given as a starting point in the derivation of the theoretical equation which relates ball size to feed size. A discussion with F. C. Bond led to the following clarification: Bond postulates that "the breaking force exerted by a ball varies . . . as the cube of its diameter . . ." and that the force in pounds per square inch required to break a particle varies . . . as its diameter squared."

Jan 5, 1959

A week-long educational program and two-day symposium on applying the fluidizing reactor to the minerals industry drew more than 100 engineers to the University of Arizona at Tucson several weeks ago. The educational program, intended for engineers who will work closely with the reactor, attracted registrants from all sections of the U. S. and Canada. Meeting at the College of Mines on February 23 for a full week of intensive classwork, the engineers ploughed in with enthusiasm. Eight hours daily of lectures and laboratory work were followed by a generous helping of homework supplied by Professor Sigmund L. Smith, who directed the course. The study program was completed on Friday and the following Monday marked the start of a symposium of technical papers covering a wide variety of operations and new ideas.

Jan 4, 1959

By G. W. Mao, A. M. Gaudin, D. W. Fuerstenau

Activation of sphalerite with copper salts has long been thought of as a chemical reaction of the following form: ZnS + Cu++ [=] CuS + Zn++ [ 1 ] Early experimentation1-3 showed that the reaction seemed to be stopped by the coating of insoluble copper sulfide, but since the analytical methods were crude, it was only surmised that the reaction could proceed by diffusion. Probably the most conclusive evidence for reaction (Eq. 1) was obtained by Cooke,4 who found a stoichiometric replacement of Zn++ by Cu" after 50 days' reaction at about 100°C. Cooke also found the sphalerite to be covered with a rather thick coating of covellite, which in¬dicates that activation is a continuing replacement of Zn++ by Cu" rather than diffusion of Cu" throughout the sphalerite lattice. However, the occurrence of diffusion at high temperatures has been observed.5,6

Jan 4, 1959

By Peter B. Nalle

Over a period of years the Crestmore plant of the Riverside Cement Co. has been supplied with limestone from the Chino limestone bed. The limestone bed dips about 40º and extends 1500 ft along the strike. Thickness of the bed is such that horizontal distance from footwall to hanging wall varies from 400 to 1200 ft. When the new room and pillar mining system was instituted the haulage units used for development were model C Tournarockers. Four of these diesel units were purchased with the idea of using them solely for development work since it was realized that they would have to be supplemented by additional, and perhaps larger haulers.

Jan 4, 1959

By William N. Matheson

The major consideration in any management and engineering decision is the economic evaluation of factors. The right decision is the best cost decision, provided of course that it is the safest. Changes, improvements, and advances in mining technology, as in any business, come about through the pressure of economics in combination with the inventiveness and engineering abilities of efficient mine operators. Without proper economic evaluation and an appreciation of profit and loss of an operation, advances in mining methods would come about at a slow pace, if at all.

Jan 4, 1959

By J. L. Gillson

Historically, rock deposits and sand deposits of titanium minerals came into production about the same time, although there may be some argument as to what is meant by production. Beach de- posits of heavy minerals in India (Figs. 1-4) and Brazil (Figs. 5) were worked for monazite about the turn of century, but as there was then no market for titanium minerals, these were thrown away. The rock rutile deposits at Roseland, Va., Fig. 6, were worked to supply rutile for titanium chemicals and for coloring ceramics long before there was a titanium pigment business. The pigment industry started about the middle twenties, both in Europe and the U. S., and almost simultaneously the rock deposits at Ponte Vedra Beach near Jacksonville, Fla., were worked for titanium content. Since those days, production from both types of deposits has continued to grow at a rapid rate; many deposits of both types have been found, and reserves have grown to very large figures. In total tonnage of reserves, there is no doubt that the rock deposits are far ahead of the sand deposits; nevertheless there is a very large tonnage of commercial sands available. It is the quality of titanium mineral in the sand and the relatively lower costs of operating sand deposits that have kept them abreast, at least in annual tonnage produced, with the rock deposits.

Jan 4, 1959

By John Dasher, M. C. Chang

The Crucible mine in Pennsylvania, operating on Pittsburgh seam coal, is rated at 5000 tpd. The washing plant, built in 1943, is rated at about 400 tph, using hydroseparator boxes to wash the coarse coal (4 x 5/16 in.) and hydrotator units for the fine coal (5/16 x 0). It is generally acknowledged that gravity concentration equipment cannot be used efficiently to beneficiate coal finer than about 65 mesh. Before the present flotation circuit was installed, Crucible recovered its fine coal slurry, predominantly -24 mesh material, by passing it through a battery of five 14-in. and one hundred and ten 3-in. Hey1 & Patterson cyclones in parallel with a 75-ft Dorr thickener. About two thirds went to the cyclones and one third to the thickener. Underflows from cyclones and thickener were filtered, respectively, in one 12-disk Eimco and two 4-disk Oliver filters fitted with stainless steel cloth. The resulting cakes were added to the coarse metallurgical coal. The filtrates, overflow from the 3-in. cyclones, and thickener overflow were recycled to the coarse coal plant.

Jan 3, 1959

By Igor Plaksin

Interaction of sulfide minerals and native metals with reagents in flotation is largely determined by particle-surface changes resulting from action of the medium and dissolved gases. A number of early studies were devoted to the selective action of various gases on minerals.1 Mc- Lachlan2 paid attention to oxygen as the most active gas affecting flotation properties of sulfide minerals.

Jan 3, 1959

By R. E. Crater

Brown, Gaudin, and Loeb in their study of intergranular comminution by heating attempt to find one explanation for all types of rock in terms of the properties of the phases present. The only necessary condition for intergranular cracking by heating is the setting up of high stresses at the grain boundaries. Such stresses may be set up in multiphase isotropic mixtures if the thermal expansions of the phases are different, in non-cubic single phases because of the anisotropy of thermal expansion in the various crystallographic directions, and in materials containing quartz because of the a-ß transformation at 575°C. In addition, for intergranular comminution by heating, the cooling and not the heating is most important.

Jan 3, 1959

By L. Graydon Carpenter, Donald E. Garrett

Probably the largest single tungsten deposit in the U. S. is one that has yet to produce any tungsten; it is not even listed in tables showing U. S. reserves. This deposit is at Searles Lake, Calif., where the brine contains about 70 ppm WO3. Small though the concentration is, the amount of brine in the lake is so great that it is estimated at 170 million lb of WO3 (8.5 million units), equaling the total of all other known reserves in the U. S. This dry lake is located in the basin formed by the Argus and Slate ranges in the northeastern corner of the Mojave Desert (Fig. 1). It consists of a massive salt body some 35 sq miles in extent, varying in thickness from 0 to 120 ft and containing more than 3 billion tons of salt. A central section of about L. G. CARPENTER and D. E. GARRETT are with the Research Dept., American Potash & Chemical Corp., Trona, Calif. TP 47881. Manuscript, Nov. 4, 1958. AlME Trans., Vol. 214, 1959. 8 sq miles is exposed salt; the remaining area is overlain by mud. Except for the exposed sodium chloride (10 to 15 ft thick) the body consists of a very complex and heterogenous mixture of soluble crystals, containing at least eight major phases. It is only about 53 pct solid, the voids being occupied by a dense brine which is the raw material for two chemical companies operating in the valley.

Jan 3, 1959