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By Pramod C. Thakur

Coal is a major source of energy in the world today and will, undoubtedly, continue to be so for the next few centuries. Naturally, a great number of studies has been made of its physical and chemical properties. Unfortunately, the work on technical properties which influence the mining of coal and the consequent yield of inflammable gases and respirable dust particles has not progressed at a comparable pace. Coal is a brittle material. Irrespective of the mechanism of breaking coal, some dust is always produced. In mining parlance dust is defined as solid particle, smaller than 100 microns (micron = 10-6 meter), in size Coal dust, when raised into a cloud, creates two well known hazards in mines, namely, the coal dust explosion and Coal Workers' Pneumoconiosis (CMP). The latter is, perhaps, the greatest environmental hazard in U.S. coal mines today. In this context it is not only natural but also necessary to investigate the proneness of a coal seam to respirable dust production. It has been established that the amount of dust produced is a function of two groups of variables (1), (2), viz. (1) Material dependent variables, e.g., moisture content, compressive strength, hardness, etc. (ii) Breaking mechanism dependent variables, e.g., type of machine, depth of cut, etc.

Jan 1, 1973

By Walter W. Fisher

Cement copper was flash roasted in a vertical tube furnace to convert the copper to acid-soluble oxides as part of a postulated process for refining cement copper by oxidation roasting, acid leaching, and electrowinning. The results of the study showed that the oxidation was a linear function of oxygen concentration between 0 and 20 percent, but above 20 percent oxygen there was no further increase in oxidation. Therefore, air was the optimum oxidizing atmosphere in this flash roasting system. The oxidation followed a parabolic rate law as the roasting temperature was increased from 400° to 800° C. Extrapolation of the data, based on the parabolic law, indicated that at 400°, 500°,600°,700°, and 800° C, the roasting times required for complete conversion to soluble oxides were 75, 37, 21, 7.7, and 4.6 seconds, respectively. Cyclic-roasting test results did not substantiate the predictions obtained through data extrapolation.

Jan 1, 1973

By D. A. Karvonen

In 1970, the Government of Saskatchewan instituted a program aimed at resolving the dilemma of excess productive capacity over the market demand which existed for potash produced in Saskatchewan. The two primary elements of the program were prorationing of potash production to market demand and a minimum selling price. The paper reviews the factors, both local and international in nature that led to the introduction of the program. The licensing mechanics and the operation of the program, along with the changes that have been introduced in two and one-half years of operation, are discussed. Attention is given to the results of the controls as they affect the industry and the province. Also discussed is the outlook for Saskatchewan potash in world markets.

Jan 1, 1973

By J. H. Parliament

"The 15,000-tpd Similkameen open-pit copper mine, 10 miles south of Princeton, B.C., started production during 1972. The two main ore zones are separated by the deep canyon of the Similkameen River, with the Ingerbelle or western deposit being mined first. The location, design and construction of the plant were complicated by the steep terrain and the situation of the orebodies. Mining, utilizing 10-cu.yd electric shovels and 100-ton electric-wheel trucks, is conventional. Closely integrated with the preproduction mining was the construction of a 4-mile section of main highway to bypass the Ingerbelle pit. This entailed a very large fill, placed with mine equipment. Ore is crushed to minus 9 inches, stockpiled and reclaimed for direct delivery to three 32-ft-diameter by 14• ft single-stage autogenous grinding mills, each driven by two 4000-hp motors. Because of the friable ore in the upper part of the mine, 4-inch balls are added, with higher than design throughput attained. Classification is by 91>-inch spiral classifiers and cyclones. The flotation section comprises three parallel lines of ten 400-cu.ft rougher- scavenger cells and a single line of 100-cu.ft cleaner and recleaner cells. Concentrate is transported in end dump, closed trucks to Vancouver for dockside storage prior to shipment to the smelter. Tailings are piped across the canyon on a suspension bridge and through a tunnel to an empoundment area. Water is reclaimed and returned to the concentrator, forming a closed system. Dams are raised with cycloned ands, with the downstream section compacted."

Jan 1, 1973

By William I. Weisman

The annual consumption of fluorspar in the United States, in the last 10 years has doubled. In 1971, when 1,344,742 tons were consumed, almost 45 percent of this amount was used in the production of steel and nearly 50 percent was consumed in the manufacture of hydrofluoric acid. Of the hydrofluoric acid produced, about one-third was used in the manufacture of aluminum electrolytes for production of primary aluminum metal and the balance was consumed in the manufacture of a variety of fluorocarbons and other chemicals. A small amount of fluorspar, constituting less than five percent of total consumption, was used in the foundry industry, and in the manufacture of glass, enamel, cement and other products. It is apparent that a continuing supply of fluorspar will be required to meet the demands for these vital metals and chemicals in our expanding industrial society. Domestic fluorspar production meets only approximately 20 percent of our needs. Hence, it is essential that the United States maintain a healthy domestic fluorspar industry in order to have adequate domestic reserves available at times of emergency and to protect this country from becoming solely dependent on foreign sources for this strategic commodity.

Jan 1, 1973

In the Ora Banda area of the Eastern Gold- fields, the ultramafic rocks tend to be more deeply lateritized than most of the surrounding rock types, and lateritic nickel concentrations have been formed. Extensive drilling_has shown that, of the two intermixed suites be- neath the laterite - an extrusive peridotite- pyroxenite suite and an intrusive, highly magnetic dunite - the latter weathers to a more nickel enriched laterite. The top horizon I of the laterite consists of ferricrete. Horizon II consists mainly of bands of secondary silica in a clay matrix, formed in the reworking zone around the water table and stranded as the weathering profile migrated downwards. Horizon III ('ºaprolite") is composed of serpentinite, magnesite, iron oxides and silica, and grades dowil to the fresh bock composed variously of olivine, ser- pentine, talc, amphibole-chlorite and iron oxides. The main locus of nickel deposition is the zone containing the bottom of horizon II and the top of horizon III. The water table is also at this general level. .

Jan 1, 1973

By Floyd M. Thorman

Gypsum is the crystalline chemical compound CaS04?2H20. A close chemical relation - and frequently occurring with Gypsum ? is Anhydrite which is Cask. Gypsun has wide commercial use because relatively simple heat processing reduces it to Plaster of Paris. While Anhydrite can be converted to Gypsum and thence to Plaster of Paris, the procedure is not simple and is quite costly. Anhydrite, however does have use in the agricultural field and in the Portland Cement industry. Occurrence of Gypsum in the earth structure is usually near or at the surface. Most underground mining is at 60 to 100 feet although one mine in southwest Virginia reaches a depth of 1300 feet. Gypsum is one of our softest minerals, rating only 2.0 on the Mohs scale of hardness. Specific gravity is 2.3 to 2.4. It is soluble in water but only slightly so. Interestingly, it is more soluble in cold water than in hot. For example, one part Gypsum dissolves in 370 parts water at 106° Fahrenheit while at 212°F. the water requirement is 452 parts. Compressive strength of massive Gypsum runs about 3000 lbs. per square inch. Color ranges from grey and brownish-grey to white.

Jan 1, 1973

By J. A. Cavallaro

This Bureau of Mines report describes the preparation characteristics of 10 coal samples collected from the significant coal-producing mines of Lucas, Mahaska, Marion, Monroe, and Wapello Counties in Iowa, with special emphasis on physical desulfurization. All 10 samples were of high sulfur content as received, ranging from 4.2 to 10.4 percent; the organic sulfur content ranged from 0.8 to 3.8 percent. The pyritic sulfur content of the samples could be appreciably reduced by crushing and washing and provided pyritic sulfur reductions ranging from 36 to 75 percent. Crushing to 3/8-inch top size and removing the sink 1.60 specific gravity material would provide float coal products containing 3.5 to 6.0 percent sulfur. However, these coals could be burned at utility plants utilizing SO2 removal processes with efficiencies ranging from 70 to 88 percent and still be in compliance with the current Federal SO2 emission regulations for stationary sources.

Jan 1, 1973

The introduction of cement into underground backfilling at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited mines to improve mining efficiencies gave rise to several major problems, the magnitude of which had not been anticipated. These problems were 1. A loss of recovery in the milling circuit due to the presence of cement 2. The presence of cement-rich slime layers on the surface of the fills 3. The introduction of a safety hazard due to the slippery nature of the surface of cemented fills 4. The deposition of cemented slimes on the levels and in underground sumps and dams. The loss of revenue due to decreased metal recoveries considerably offset the gains from increased stoping efficiencies and the use of cement was substantially reduced while, (a) the Metallurgical. Department attempted to identify the chemical nature of the problem and overcome it, and (b) the Mining Department investigated methods of reducing cement contamination of the ore stream. As a part of this investigation the Mining Department added polymeric flocculants to the cemented fill pulp. Testwork was carried out in the following steps 1. The available Alfloc polymers were screened to determine which was the most effective and what was its optimum dosage rate. 2. This polymer was used in the laboratory to determine the reduction of surface slime, clarity of water, and effects on strength and percolation of fill. 3. Fills were placed underground to substan- tiate the laboratory work. /+. The polymer was then added to all cemented fills going underground to study its effect over a long term. The use of flocculants not only improved the distribution of cement in the body of the fill, but also the distribution of the fines fraction of the filling material, practically eliminated slippery surfaces and improved the clarity of the drainage water. Flocculant is now added to all cemented fills and restrictions on the use of cement are gradually being lifted.

Jan 1, 1973

By J. R. Ross

The extraction and recovery of nitrate from waste solutions generated in the production of titanium were investigated using solvent extraction techniques. Laboratory studies and continuous tests in a small solvent-extraction system showed that up to 98 percent of the nitrate can be selectively extracted by a solution of tributyl phosphate in kerosine. The extracted nitrate can be recovered as nitric acid, at concentrations suitable for reuse, by stripping the loaded organic with water.

Jan 1, 1973

By Salim Akhtar

The operation of a mineral processing plant with a complex flowsheet is represented by a mathematical operator. Such a representation permits a quantitative evaluation and monitoring of the separation processes in different sections of a processing plant, and gives an overall separation efficiency of the plant.

Jan 1, 1973

By L. E. Cardwell

This publication contains routine analyses and related source data for 299 natural gas samples from 22 States and three foreign countries. All of the samples were collected during calendar year 1972 as part of a continuous survey of the free world for occurrences of helium in natural gas. This survey has been conducted in the United States by the Bureau of Mines since 1917. In late 1965, the survey was expanded to include foreign gasfields. The analyses published herein were made by mass spectrometer and a special helium analysis apparatus, which are described in Bureau of Mines Bulletins 4863 and 576.4 Fourteen previous publications have presented the results of 9,902 gas analyses prior to 1972. The first three, Bulletins 486,5 576,6 and 617,7 contain analyses and related source data on 5,218 gas samples collected from

Jan 1, 1973

By R. C. Wang

Solid-liquid flow in different pipe geometries was investigated. This investigation was conducted by measuring delivered solids concentration and head loss. The delivered solids concentration was measured to study the effect of pipe geometry on the minimum carrying velocity above which solids do not lag behind the fluid. Head loss was measured to study the effect of pipe geometry on the friction loss. A mathematical formula was developed for determination of the minimum carrying velocity. Darcy-Weisbach's equation and Durand's equation were used for comparison of head losses of pipe shapes. Of the different pipe shapes studied, each having the same interior cross-sectional area, the rectangular pipe with the wide side oriented as the base yielded the lowest minimum carrying velocity at high solids concentrations. The minimum head loss at low velocity and high solids concentration also was attained with this pipe. Although the circular section is known to be the best for transporting liquid only, the present study suggested that pipe geometry is a factor in lowering the operating velocity and reducing head loss in solid-liquid flow.

Jan 1, 1973

[Adams, Dell H Consolidation Coal Co., 43 Denver Tech Center, Englewood, Colo. Adams, Douglas K General Electric Co., Box 2331, Denver, Colo. Adams, Kenneth L Peabody Coal Co., 33 Carnation Dr., Belleville, Ill. Aggen, Marshall J Marathon LeTourneau Co., Rt. 4, Box 1188, Henderson, Texas Ahlborg, William Joy Mfg. Co., 580 Denver Club Bldg., Denver, Colo. Albrechtsen, Ray H Mt. States Resources Corp., 2330 So. Main, Salt Lake City, Utah Alford, Eugene C Pittsburg & Midway Coal Mining Co., 2025 TenMain Center, Kansas City, Missouri Allen, Earl W Mine Safety Appliance Co., 5708 East 7th St., Tucson, Arizona Alston, George Mine Safety Appliances Co., 400 Penn Center Blvd., Pittsburgh, Pa. Amerman, Richard W Utah International, Inc., Box 155, Fruitland, New Mex. Anderson, G. A Walker Bank & Trust Co., Drawer M, Price, Utah Anderson, John S Utah International, Inc., 550 California St., San Francisco, Calif. Anderson, Robert Mine Safety Appliances Co., 1881 West North Temple, Salt Lake City, Utah]

Jan 1, 1973

By W. A. Hoyer, G. A. Lock

Laboratory and field tests have shown that it is feasible to log for copper in a qualitative way using the techniques of neutron activation analysis. Laboratory tests showed that the 0.51 and 1.04 mev gamma rays of 62Cu and 66Cu, respectively, could be diagnostic. However, in the core holes, the detection of copper was limited to 0.3% concentration because of interferences from the 18Si and Al gamma rays. Both stationary and continuous logs were made, but only the stationary data yielded a recognizable copper response. This response consists of a combination of two effects-the direct response from copper at 0.51 mev and an increase in low energy gamma ray absorption due to mineralization. Both low energy chemical (PuBe) and high energy accelerator neutron sources were used for the laboratory and field tests, while the same 2 X 5 in. Nal scintillation detector served for all the tests. Potential improvements in copper detection might be possible with solid state gamma-ray detectors which have better gamma ray resolution but much less detection efficiency. This type of activation logging requires complex equipment and trained personnel to conduct field operations and may find application where coring is difficult or prohibitive.

Jan 1, 1973

By A. T. Yu

The quest for ore in an open pit is fundamentally an earth moving proposition. This thesis is vividly underscored by the rapidly increasing volume of waste to be removed in newer mines, where in some instances waste to ore ratios have reached as high as 20 to 1. Continuing depletion of high grade reserves, greater demand for raw materials, coupled with ever climbing labor costs, have made the problem still more pronounced and the need for more effective means of earth moving in an open pit even more acute. A conservative approach to the problem has been to upgrade the sizes of conventional earth moving equipment such as shovels and trucks. In many open pits, particularly in the C.S., this has been responsible for the generally down- ward trend of earth moving costs. None the less, the investment costs of these machines are high, and their gigantic engines are seldom fully utilized. Moreover, a large number of operators are required and maintenance remains relatively high. Unfortunately most people have felt that no other viable alternative was in sight within today's technological capabilities.

Jan 1, 1973

By P. D. Bergman

To assess the efficacy and economics of producing power from coal, four open-cycle magnetohydrodynamic (MHD) processing schemes were selected for study. Each involved a different mode of coal combustion and level of gas cleanliness. The options considered were: (1) coal burned in a slagging combustor; (2) suspension gasification with slag removal prior to combustion; (3) parallel cyclone combustors, one operating fuel rich and the other operating with excess air; and (4) suspension gasification by the hot exhaust gases from the MHO duct with ash removed prior to combustion. Option 1 has the highest ash content in the combustion plasma and as a result would have the greatest operational difficulties associated with it. Options 2 and 4 have the cleanest MHD combustion plasma. For coal priced at $4/ton, the power generating cost of option 4,11.78 mills/Kw-hr, is the highest, with Option 1, at 9.04 mills/kW-hr the lowest. These costs may be compared with a conventional power cost of 9.92 mills/kW-hr for the late seventies. Capital costs of three of the four options were competitive with those of conventional thermal power plants employing stack gas S02 cleanup systems. Option 2 has the most favorable combination of operating characteristics and power cost. It was concluded that a clean, high-temperature working fluid can probably be produced from coal without leading to depressed system efficiencies and exorbitant capital costs.

Jan 1, 1973

By James R. Strong

Before getting into the subject of packaging and materials management, please permit me to introduce you to MICRO SWITCH. MICRO SWITCH, A Division of Honeywell Inc. is located in Freeport, Illinois. We manufacture and market thousands of types of precision snap-action electrical switches. Most of them are used as components by other manufacturers in industrial and commercial products. MICRO SWITCH also offers a broad line of industrial control devices including heavy- duty limit switches, relays, manual controls and proximity switches. Other product lines are solid state keyboards for the computer industry and high-performance d.c. motors used in computer related equipment. So you can see that we are a component manufacturer. With the exception of the keyboards, every one of our products would "fit comfortably into a breadbox." Some are so tiny that one could easily fit several thousand into a man's hat. In my position as supervisor-packaging. package design, and materials handling engineering, I am actively involved in package design projects, parts handling design projects, and numerous activities involving departmental layouts, storage facilities, and material handling equipment. Two package design technicians, a materials handling engineer, and a materials handling technician make up the technical staff.

Jan 1, 1973

By C. M. Frost

Crude shale oil prepared by gas-combustion retorting of Colorado oil shale was hydrogenated over a cobalt molybdate catalyst at an operating pressure of 1,000 psig, temperatures of 781° and 761° F, and liquid hourly space velocities of 0.10 and 0.05 Vo/Vo/hr, respectively. The yields of total liquid products and the amounts of nitrogen and sulfur removed were comparable with those obtained at an operating pressure of 3,000 psig and a liquid hourly space velocity of 1.0 Vo/Vo/hr. Approximately 1.5 times as much gasoline was produced at the lower pressure and space velocities.

Jan 1, 1973

By R. R. Schehl

The Bureau of Mines has developed a quantitative Analysis for pyrite in coal by X-ray diffraction that can be accomplished in little more than 1 hour. To minimize the sample analysis time, data processing has been completely computerized with pertinent output information displayed on a VR12 cathode-ray tube display. Use of this computerized system is not only advantageous during the experimental stages of the pyrite analysis project but would also be essential if the X-ray diffraction procedure is accepted as a standard method of analysis.

Jan 1, 1973