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By R. G. Sandberg

Many gold-bearing ores throughout the Western United States contain small quantities of mercury. The presence of mercury not only decreases the gold-loading capacity of the activated carbon, but complicates the fire refining of cathodes and creates a potential health hazard. The Bureau of Mines investigated methods to limit mercury extraction during gold ore leaching and to remove mercury from cyanide leach solu-tions. Mercury dissolution was reduced from 40 to 10 pct by decreasing NaCN concentration from 20 lb to 0.34 lb per ton of solution at a pH of <11. When 0.1 lb CaS per ton of ore was added to a leach slurry, mer-cury extraction was reduced from 27 to 0.4 pct. Less than 0.5 pct of the mercury was solubilized when <0.1 lb CaS per ton of are, along with lime and NaCN, was added to a simulated grinding circuit.

Jan 1, 1984

By D. J. Bauer

A primary amine extraction system was investigated for fractionating a cerium-group, lanthanide sulfate mixture. Addition of diethylenetriaminepenta-acetic acid (DTPA) to the amine extraction system resulted in separation factors as high as 5.4 for lanthanum-cerium, 8.0 for cerium-praseodymium, 3.7 for praseodymium-neodymium, and 7.0 for neodymium-samarium. In multistage studies on a cerium-free lanthanide mixture, 96 percent of the lanthanum was recovered with a purity of 95 percent.

Jan 1, 1968

By J. G. Eisele

Solvent-extraction characteristics of dodecyl phosphoric acid (DDPA) were investigated to determine its potential as a fractional or selective extract-ant for individual elements in a rare-earth-yttrium mixture. The DDPA is an effective extractant for splitting rare-earth mixtures into light and heavy subgroups. Yttrium normally extracts with the heavy rare-earth elements but may be shifted toward an extraction sequence with the light rare-earth elements by increasing the pH. Elements in the light and heavy ends of the rare-earth series can be separated from middle-group rare-earth elements by using diethylenetriaminepentaacetic acid (DTPA) as an aqueous phase counter-extractant. Hydrogen-ion dependency of the distribution coefficients differs from that reported for similar systems at tracer-level concentration.

Jan 1, 1965

By G. E. McClelland

The Bureau of Mines investigated chemical methods for producing high- purity gold from precious-metal-bearing zinc precipitates and steel wool cathodes. Precious-metal-bearing zinc precipitates and steel wool cathodes are unrefined products from conventional cyanidation and heap leaching-cyanidation operations. The zinc precipitates contained 14,40 pct Au and 0.35 pct Ag. The precious-metal-bearing steel wool cathodes contained 20.65 pct Au and 4.84 pct Ag. The precipitates and cathodes were treated with dilute acid to solubilize the silver and/or base metals. The gold-bearing residue was leached in dilute aqua reqia to solubilize the gold. High-purity gold was precipitated from the aqua regia solution with oxalic acid, sulfurous acid, sodium bisulfite, and gaseous sulfur dioxide. The leaching-precipitation experiments recovered 99.9 pct of the gold. The gold precipitates ranged in fineness from 997 to 999 fine. The chemical refining method provides a viable technique for the smaller operator to produce high-purity gold without using pyrometallurgical refining methods.

Jan 1, 1985

By S. H. Ash

As part of the work done at the Washington coal mines during the year 1929 , a study was made of the safety practices in and about the mines . Inasmuch as electrical blasting has made considerable headway it is interesting to note the manner in which it is done and the reasons why it was discarded at some of the mines . Blasting is done at the mines in the State by means of capped fuse , electric blasting " caps , " and in some instances by electric delay detonators . Black blasting powder with fuse is used at most of the open- light mines . The use of squibs was discontinued several years ago because the coal operators , without exception , recognized the dangers incidental to their use . Permissible explosive and dynamite are also used at some of the open- light mines . With the exception of some rock work and the driving of level work in gangways and air courses the explosive is detonated by means of capped fuse .

Apr 1, 1930

By R. P. Jewett

The object of this investigation was to correlate the crushing strength of green pellets prepared from magnetite, specular and earthy hematite with the particle size of these respective raw materials. In this study no attempt was made to correlate the strength of fired pellets and particle size. The effect of particle size upon a number of fine ores and concentrates was studied. Much of the low-grade ore reserves in the Lake Superior Region must be finely ground before concentration and then agglomerated for iron and steelmaking processes. Fine natural ores also must be agglomerated. Pellets constitute an important type of agglomerate. Considerable handling occurs during screening to remove undersize and oversize pellets, and in transfering green unfired pellets from the balling machines to the heat-hardening equipment. As a result the strength of the green pellets is a factor of great importance.

Jan 1, 1961

By Phil Patton, Bill M. Stewart, Curtis Clark

Handling materials in underground mines continues to be a major safety problem. To help reduce materials-handling injuries, the National Institute for Occupational Safety and Health (NIOSH) at the Spokane Research Laboratory is developing, modifying, and testing equipment to replace the necessity of doing lifting tasks manually. To reduce single-event lift injuries, equipment having mechanical automatic weight sensing and balancing control was investigated. The Coleman manipulator was selected for testing. Modifications to the Coleman manipulator to make it more suitable for underground mine use included mobilization, self-containment, all-purpose gripper attachment, and support jacks. To reduce or eliminate the need to clean off manually the materials that commonly plug grizzly openings (timbers, wire mesh, roof bolts, and other debris), a track-guided pincher arm device was developed. The TGPA attaches to an impact hammer head, and the pincher arms are controlled by the operator of the hammer. Oversized rock can be broken with the pincher arms in the up position; the arms can then be lowered to grab and remove debris. Sweeping action to remove cohesive fines bridging grizzly openings is also greatly improved. This device is especially useful in recessed grizzlies. An industrial gun was tested to evaluate its effectiveness in breaking oversized rock. Boulders up to 76 cm in diameter were successfully broken to minus-33 cm. Although methods to control fly rock need to be developed, an industrial gun may be a safe and inexpensive alternative to breaking oversized rock in certain underground mining situations.

By Lawrence W. Scott

The performance of RETIMET metal foam as a flame arrester on explosion-proof enclosures was investigated by the U.S. Bureau of Mines both in laboratory tests and at the U.S. Mine Safety and Health Administration&apos;s (MSHA&apos;s) Approval and Certification Center, Triadelphia, WV. The objective of this research was to develop a permissible pressure vent for use on lightweight, vented, explosion-proof enclosures. In laboratory tests, four grades of RETIMET, a stainless steel foam material, were evaluated: (1) 45 NC-7, (2) 45 NC-13, (3) 80 NC-7, and (4) 80 NC-13. Explosive gas mixtures were prepared by a dynamic flow system. Ignition was by a low-voltage arc. Each grade of RETIMET metal foam successfully arrested the flame front in all methane-air tests. To evaluate RETIMET metal foam on large, commercial size enclosures,a multi compartmented enclosure was designed and tested in MSHA&apos;s explosion gallery in Triadelphia, WV. Extensive explosion testing revealed that a minimum vent-area-to-enclosure-volume ratio of 11.33 in2/ft3 is required to keep internal pressure rises below 3 psig. The RETIMET metal foam functioned satisfactorily in all tests as evidenced by the absence of external ignitions.

Jan 1, 2010

By T. T. Read

"Employee representation in the management of large mining enterprises was first introduced in organized form, by the Colorado Fuel and Iron Co. in 1915. Within the past few years a number of the larger mining enterprises have introduced similar systems and there is growing interest in the subject. This will be stimulated by the final report of the President's Second Industrial Conference, in which the following statement occurs:""The conference finds that joint organization of management and employees where undertaken with sincerity and good will has a record of success. The general principles governing such organizations are stated at length under the title 'Employee Representation. It is not a field for legislation, because the form which employee representation should take may vary in every plant. The conference, therefore, does not direct this recommendation to legislators but to managers and employees.""If the joint organization of management and employees in the plant or industry fails to reach a collective agreement, or if without such joint organization, disputes arise which are not settled by existing agencies, then the conference proposes a system of settlement close at hand and under Government encouragement, and a minimum of regulation. The entrance of the Government into these problems should be to stimulate further cooperation."""

Mar 1, 1920

By ALICE V. Petar

Like many gem materials, amber has a colorful history which may be traced through the writings of the ancients and the ornamental relics discovered from time to time. Like few gem materials, however, it is distinctly useful in products whose value has no connection with the gem industry. Long prized for its beauty, amber was fashioned into articles of jewelry and ornaments to please the fancy of ancient rulers and to find a place among treasured pos- sessions in their tombs; it has been used by adherents of various creeds for rosaries and other religious symbols; and although still sold for these pur- poses it also lends itself to such commercial purposes as raw material for varnish. Amber is only on the border-line of the mineral kingdom; actually it is of vegetable origin, having been formed as resin from trees of the conifer family that existed during the Tertiary period. It is the hardest of the fos- sil gums. The United States produces no amber, although a few occurrences are known. Most of the world's supply comes from East Prussia, where it is ob- tained from both land and sea. For many years pieces of amber were gathered from the Baltic by fishermen and deep-sea divers; and although about 10 per- cent of the Prussian amber is still recovered from the sea, most of the out- put is mined from open pits on the Samland Peninsula.

Jun 1, 1934

By Marcia L. Harris

Toxic fumes produced by detonating explosives in surface mining and construction operations pose potential hazards to workers and the public. Blasting operations produce both toxic and nontoxic gaseous products; the toxic products are mainly carbon monoxide (CO) and the oxides of nitrogen (NOx). Since 1988, there have been 17 documented incidents in the United States and Canada in which carbon monoxide (CO) is suspected to have migrated through ground strata into occupied enclosed spaces as a result of proximate trench blasting or surface mine blasting. These incidents resulted in 39 suspected or medically verified carbon monoxide poisonings as well as one fatality. At worst people may be fatally poisoned and the least to be expected is increased public objections to blasting. Local and state agencies could demand a cessation of the blasting requiring more expensive mechanical means to break the rock. This paper discusses the most feasible means of preventing CO migration, mitigating CO that has migrated, and detecting CO in an underground enclosed space and may help reduce the exposure of unsuspecting area residents to carbon monoxide and help prevent the implementation of unnecessary regulations and limitations on blasting. Single-hole shots and small-scale multiple-hole blasts were performed that indicate promising means of prevention and mitigation.

Jan 1, 2008

By Gary L. Hundley

As part of the U.S. Bureau of Mines program to reduce the Nation&apos;s reliance on foreign supplies for critical metals, a procedure was devised to separate and recover critical metals from mixed and contaminated super alloy scrap. The process uses both pyrometallurgical and hydrometallurgical methods to treat the scrap. The mixed scrap is converted to a matte containing 4 to 7 pct S by adding S directly to the molten metal. This matte is then granulated and ground to a minus 35-mesh particle size and leached with an HCI-CI2 solution. This process takes essentially all the Ni, Co, Cr, Fe, AI, and Mo into solution in a 3-h leach, leaving W, Ta, Ti, and Nb (Cb) in the residue. The Mo is recovered from the chloride leach solution by solvent extraction, and the Cr and Fe are recovered together by precipitation. The Ni and Co can be recovered individually by an existing solvent extraction-electrowinning process. The W is recovered by a caustic leach of oxidized Cl2 leach residue.

Jan 1, 2010

By G. R. Hopkins

"Summary An apparent decline in fuel efficiency at refineries, which first became came evident in 1930 and continued through 1933, was checked in 1933 when the average amount of heat needed to refine a barrel of crude oil amounted to 660,000 B.t.u. This compares with an average requirement of 692,000 B.t.u. In 1932 and with a low of 639,000 B.t.u. in 1929. (See fig. 1.) The improvement in fuel economy in 1933 probably was closely related to the increase of 5 per cent in crude runs to stills. As much of the fuel burned at refineries is utilized for purposes other than under crude-oil stills and in relatively stable amounts, it is evident that a material increase in crude runs will usually reflected in a decrease in average fuel requirements. Another factor which has influences fuel economy at refineries in the past is the trend in cracking, a refining process requiring more than the average expenditure of heat. In 1933 production of gasoline by cracking increased slightly, but no appreciable rise in heat requirements resulted as an equivalent amount of fuel was saved in improved technique, particularly in the field of heat exchange.Since the beginning of the refining industry, the transition in fuels has been from solid to liquid to gaseous; in other words, the leadership was first held by coal, then passed to oil, and is now held by gas. In 1933, 54.7 percent of the total heat units generated came from gas, 39.0 percent from oil (including acid sludge), and 6.3 percent from coal and coke. The principal change in the relative importance of the various refinery fuels in recent years has been the rapid growth in consumption of refinery or still gas at the expense of all the other common fuels. Still gas owes its ascendency to its cheapness and availability, and probably it would have become the primary refinery fuel years ago if recovery methods had been perfected. The relative importance of coal showed a small increase in 1933, the first gain recorded since these surveys were inaugurated in 1925. The increase in use of coal was undoubtedly due to increased operations at plants using it,"

Feb 1, 1935

By Wesley A. Grosh

The Vest nickel prospect, in Floyd County, Va., was discovered about 25 years ago. Limited exploration of the deposit had indicated some appreciable nickel mineralization in the sulfide ore. The property was examined on March 9, 1943, by an engineer of the Bureau of Mines in company with C. W. Vest, owner of the property. A limited exploration program was recommended. Two holes totaling 320 feet were diamond-drilled in January 1944. Drilling indicated the sulfides are sparsely disseminated. The only nickel values of interest were at the old prospect shaft.

Jan 1, 1949

By A. J. Farstad, R. F. Kehrman

Characteristics of metal/non metal mines were evaluated to determine the suitability of applying the U.S. Bureau of Mines electromagnetic location system to the problem of locating trapped driers in metal/non metal mines. Statistical distributions of mine depths and overburden conductivities show that the existing USBM EM system is inadequate for most metal/non metal mines. Alternate approaches to trapped miner location in deep mines were identified and subsequent field tests were conducted at six (6) mines to evaluate their feasibility. The approach considered to be the most promising is one which utilizes the existing manpack transmitting system, modified slightly for a dual frequency output, in conjunction with a sophisticated signal processing receiver on the surface. The main advantage of staying with a "through the earth" approach is that the underground equipment can be kept simple, easily maintained, light- weight and inexpensive.

Jan 1, 1979

Limestone formations in the United States can be subject to relatively high horizontal stresses due to the existence of tectonic loading of the limestone strata. Underground limestone mines use the room-and-pillar method, in which 12- to 18-m-wide rooms are typically excavated. The stability of these excavations can be compromised by the horizontal stress, resulting in a rockfall hazard. Rockfalls are the cause of 15% of all reportable injuries in underground limestone mines. Horizontal stress related damage can occur in the form of guttering along one or more sides of an excavation, roof beam buckling or oval shaped roof falls, with the long axis perpendicular to the major horizontal stress. Numerical analyses show that the pillar layout and orientation of the mine workings have an effect on the horizontal stress distribution within the roof. The effects of high horizontal stresses can be mitigated by orientating the heading development direction parallel to the maximum horizontal stress, reducing the number of cross-cuts and offsetting the cross-cuts to limit the potential lateral extent of horizontal stress related roof falls. The modeling approach described in this paper can be used as a tool to evaluate potential roof failure and optimize the stability of room and pillar layouts.

Jan 1, 2008

By P. L. Woolf

Two blast furnaces, one a. commercial furnace and the other the Bureau of Mines experimental furnace, were successfully operated with extremely low slag volumes. The lowest slag rate obtained on the industrial furnace was 335 pounds per ton of metal. Using the same burden materials a 245-pound slag volume was achieved on the furnace. The coke rate saving and increase in productivity resulting from lowered slag rates are discussed as well as the factors limiting a low slag practice.

Jan 1, 1965

By Martin H. Stanczyk

Acid leaching of selected copper sulfide minerals, impure copper sulfide flotation concentrates, and a cement copper precipitate at elevated temperatures and pressures was investigated. Copper extractions of 97 to 99 pct were obtained by leaching chalcopyrite and the flotation concentrates with water under oxidizing conditions at 200° C for 30 to 60 min. In tests with bornite, chalcocite,and cement copper, addition of sulfuric acid or pyrite to the autoclave was required to obtain similar copper extractions. The chemistry of leaching copper minerals was studied. It was determined that different copper sulfides altered to covellite as one step in their dissolution.

Jan 1, 1963

By D. P. Desmond

The U.S. Bureau of Mines investigated leaching automobile catalysts with sodium cyanide (NaCN) solutions at high temperatures to recover platinum-group metals (PGM). The feed was virgin monolith rejects, used monolith, and used pellet catalysts. Leaching with a 5-pct NaCN solution for 1 h at 160° C dissolved over 97 pct of the PGM in the virgin monolith, over 85 pct of the PGM in the used monolith, and over 90 pct of the PGM in the used pellet catalyst. Over 99.8 pct of the dissolved PGM was recovered as a precipitate by heating the solution to 250° C for 1 h in an autoclave. The cyanide complexes were decomposed, and free cyanide was destroyed.

Jan 1, 2010

By F. L. Wideman

Output of ore and waste from metal and nonmetal mines in the United States continued an upward trend and established a new high. The tonnage of ore handled increased 6 percent over that moved in 1964 and the tonnage of waste rose almost 10 percent. Earth moving by these two activities exceeded 3.2 billion tons, an increase of 7 percent over the 1964 total. Crude material from which metal or nonmetal products were derived continued to be about 75 percent of the total material handled. In 1965, surface mining methods were used to produce about 93 percent of the ore, 99 percent of the waste, and 95 percent of the total material handled. These percentages have remained almost constant since the beginning of this decade.

Jan 1, 1966