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By S. W. Lambert

In this Bureau of Mines investigation, production was monitored for 1 year at over 30 coalbed gas-drainage boreholes located in Alabama, Pennsylvania, and West Virginia. Results indicate that the quality of data gathered from such wells can be improved greatly if potential problems are anticipated and prevented in the early stages of well production. Major water-monitoring problems include solids buildup, freezing, the presence of gas in surface waterlines, and improper pumping interval settings. Such problems may be avoided by incorporating in the original well design waterline filters, sand screens, separator tanks, and systems to automatically control pumping intervals. Problems related to measurement of coalbed gas flow include large quantities of water vapor contained in the gas, especially during winter months; freezing and subsequent obstruction of flow; sudden, uncontrolled release of gas pressure; and solids buildup in metering equipment. The installation of commercially available items, such as filters, separators, and insulation, and the thoughtful application of a basic knowledge of coalbed gas reservoir characteristics will prevent most production-monitoring problems.

Jan 1, 1978

By Joseph E. Matta

The Bureau of Mines conducted tests using a tracer-gas technique to measure the effectiveness of the jet fan, which is often employed in mines to ventilate dead headings. Results of these tests show that jet fans can (1) ventilate dead headings beyond the maximum penetration distance indicated by smoke-tube detection of air movement, and (2) redistribute available fresh air through larger working areas. However, if the fresh air base is insufficient, the fan will merely recirculate the contaminated air and disperse it over a larger volume.

Jan 1, 1978

By Charles C. Hwang

In this Bureau of Mines report, a previously developed theory of reverse stratified flow in ventilated duct fires is applied to mine-related ventilation systems that utilize an exhaust fan to supply the forced airflows. The coupling between a fire and the ventilation airflow in a single-entry duct is analyzed to relate the air velocity in the absence of a fire to air velocity during a fire. By combining the derived coupling equations with the results of the previously developed theory of reverse stratified flow, it is possible to calculate critical flow velocities required to prevent reverse stratified flow in the event of a duct fire. The sample calculations shown agree with the few experimental results available from small-scale tunnel fires.

Jan 1, 1978

By W. N. Marchant

The Bureau of Mines improved removal of selenium from zinc smelter acidic gas scrubber effluent by using zinc dust to precipitate soluble selenium prior to lime neutralization. Lime neutralization alone decreased selenium in the waste water from, typically, 6 parts per million to 2 parts per million, whereas the use of zinc dust precipitant gave an effluent containing less than 0.1 part per million of selenium. The waste treatment operation first was developed on a laboratory scale and later was successfully tested at a smelter site on a 1-gallon-per-minute basis. During the research a simple and rapid means was developed for determining selenium in waste water; the technique enabled visual semiquantitative selenium determinations that later were confirmed quantitatively by X-ray fluorescence.

Jan 1, 1978

By M. M. Tilman

The Bureau of Mines conducted research to determine whether it is possible to substantially improve the fatigue resistance of lead sheet by means of surface coatings. Five types of coatings were applied to unalloyed chemical lead sheet. Flexural tests revealed that the best fatigue resistance was obtained with coatings of vacuum grease. Vacuum-grease coatings on unalloyed lead sheet resulted in fatigue resistance at least as good as that of the fatigue-resistant alloy Pb-0.04 Ca. Coated lead sheet was also tested in short-time tensile tests and in tensile creep tests. Tensile and yield strengths were increased by several of the coatings with only moderate loss of ductility. Creep resistance was also improved in varying degrees by most of the coatings. The Bureau also conducted research on the effectiveness of noise barriers by using sheet lead in combination with other materials. Noise barriers consisting of continuous-cast sheet lead with gypsum board were found to be effective and relatively inexpensive barriers.

Jan 1, 1978

By W. R. McDonald

The Bureau of Mines, U.S. Department of the Interior, conducted small-scale field tests on acidic copper tailings as part of its effort to develop, improve, and demonstrate technology for stabilizing mining and mineral-processing wastes. Two successful demonstration revegetation plots were established on an abandoned copper-tailings pond located on public land adjacent to Holden Village, Wash. The tailings were neutralized with treatments of either dolomitic lime or limerock and fertilized with processed sewage sludge and/or commercial fertilizer. Excellent plant growths covering 70 and 24 percent of the surface were achieved on 1/8-and 1-1/2-acre test plots planted in 1973 and 1974, respectively. Regar brame, Tegmar intermediate wheatgrass, and tall wheatgrass provided the best plant growth and surface coverage. The target pH of tailings neutralization was 6.8; however, good plant growth occurred in areas where the soil pH ranged from 2.9 to 5.8.

Jan 1, 1978

By P. B. Altringer

The Bureau of Mines conducted laboratory tests to devise a procedure for recovering a marketable grade of tungsten from the brine of Searles Lake, Calif. The brine contains only 56 parts per million of tungsten (70 parts per million of W03). Using ion exchange resins synthesized by Bureau chemists, 98 percent of the tungsten was extracted from the brine and 92 percent of the tungsten was recovered as a marketable iron-tungsten concentrate containing 44 percent tungstic oxide. Although major technical problems have largely been resolved, research is progressing to escalate testing in a process-development unit to provide more reliable data for an economic appraisal.

Jan 1, 1978

By Robert F. Holub

The Bureau of Mines has made a study of the magnitude of the variations of radon daughter mixtures, with the objective of determining whether these variations reflect the existing physical conditions in uranium mine atmospheres or if they are merely random or systematic errors. To accomplish this, many data have been plotted using a triangular graphing technique which shows that plateout affects RaA more than RaB or RaC, and that it is impossible to find simple correlations between working level ratios, radon daughter mixtures, and age.

Jan 1, 1978

By Ann G. Kim

The Bureau of Mines investigated factors that influence the formation of methane and other hydrocarbon gases in coal, which is an integral part of the coalification process. Coalification begins with a biogenetic stage in which plant debris decomposes and peat is formed; methane and CO2 are the predominant gases produced during this stage. During the diagenetic stage of coalification hydrogen and the hydrocarbon gases methane, ethane, ethylene, propane, propylene, butene, iso- and normal butane, and pentane are formed by dissociation of the organic material. Methane may also be produced by a secondary reaction of hydrogen with unsaturates or by the reduction of CO2. The gas contained in coalbeds is a mixture of methane, C2 through C5 alkanes, CO2, 02, N2, H2, and H2; its heating value is equivalent to that of natural gas. The gas content of coal depends on many variables, but an empirical relationship between adsorptive capacity, rank, and depth has been observed.

Jan 1, 1978

By Ann G. Kim

The Bureau of Mines investigated factors that influence the formation of methane and other hydrocarbon gases in coal, which is an integral part of the coalification process. Coalification begins with a biogenetic stage in which plant debris decomposes and peat is formed; methane and CO2 are the predominant gases produced during this stage. During the diagenetic stage of coalification hydrogen and the hydrocarbon gases methane, ethane, ethylene, propane, propylene, butene, iso-and normal butane, and pentane are formed by dissociation of the organic material. Methane may also be produced by a secondary reaction of hydrogen with unsaturates or by the reduction of CO2. The gas contained in coalbeds is a mixture of methane, C2 through C5 alkanes, CO2, O2, N2, H2, and He; its heating value is equivalent to that of natural gas. The gas content of coal depends on many variables, but an empirical relationship between adsorptive capacity, rank, and depth has been observed.

Jan 1, 1978

By S. E. Khalafalla

The ability of potentiometric, gas-sensing electrodes to reliably monitor free gaseous molecules in solution has been recently demonstrated. A gas such as sulfur dioxide from a dilute sample solution diffuses through a hydrophobic, gas-permeable membrane to an internal filling solution. The latter solution contains a sufficiently large excess of sodium bisulfite, the concentration of which can be considered constant regardless of the quantity of sulfur dioxide entering by diffusion. The electrode response is essentially due to the liberated hydrogen ions from the bisulfite-sulfur dioxide equilibrium. This Bureau of Mines report describes a new technique used to detect the formation, and to estimate the stability constant, of gas-molecule and gas-ion complexes in solution, as part of an effort to minimize the undesirable environmental impacts associated with mining and mineral processing. Although the unknown activity coefficients of the neutral and ionic species in the external solution complicate the quantitation of results, methods to circumvent these difficulties are presented. The technique is based on the isometric shift of the Nernst diagram of ion-selective electrodes to higher concentrations relative to the standard aqueous calibration curve. The method is applied to detect and estimate the formation constant of a sulfitocitrate complex, and agrees well with an independently determined stability constant of the disulfitomercu-rate complex.

Jan 1, 1978

By Benjamin W. Haynes

The Bureau of Mines conducted research to devise technology for increasing the Nation's mineral supply by recovering valuable constituents from currently discarded waste materials. Municipal solid waste (MSW), presently a major disposal problem, represents a significant source of metals, glass, and a combustible fraction that can be used to supplement coal in generating heat and electricity. As part of the total metallurgical system to treat MSW, this study evaluates the combustible fraction of MSW to characterize the various combustible components and to identify the principal sources of elements that eventually may be objectionable from corrosive or environmental considerations. Several possible sources for cadmium, chromium, cobalt, copper, lead, nickel, and zinc have been tentatively identified. These sources are pigments, inks, paper stock, and additives to plastics. A correlation between industry consumption values and measured concentrations in MSW was found for several elements.

Jan 1, 1978

By Richard G. Sandberg

Sphalerite concentrates prepared during processing of Missouri lead ores contain small percentages of cobalt and nickel which adversely affect zinc electrolysis. The Bureau of Mines has evaluated solvent extraction and precipitation techniques to remove and recover cobalt and nickel from zinc sulfate solution prior to zinc electrolysis. Prepared zinc sulfate solutions containing about 190 gpl of zinc and 50 ppm of both cobalt and nickel were treated using various combinations of complexing reagents, solvent, pH, concentration, time, and temperature. The following complexing reagents gave the best results: a-nitroso-ß-naphthol, ß-nitroso-a-naphthol, 1,2 cyclohexane dione dioxime (nioxime), di-2-pyridyl ketone oxime, and dimethylglyoxime. These reagents in suitable solvents lowered the cobalt and nickel levels to <0.1 ppm. Stripping the complexed reagents from the solvents was not possible except for nioxime. Direct addition of the appropriate reagent to the prepared zinc sulfate solution resulted in the precipitation of cobalt and nickel. Several possible flowsheets are presented for the removal and recovery of cobalt and nickel. Good zinc deposits were successfully electrowon from zinc sulfate solutions purified by solvent extraction and precipitation.

Jan 1, 1978

By R. K. Clifford

Chalcopyrite (CuFeSz) concentrates produced on the Lead Belt of Missouri typically contain 28 pct Cu and from 0.5 to 1.5 pct each of nickel and cobalt. Most of the nickel and cobalt are present as the mineral siegenite, (Ni,Co)3S4, almost none of which is recovered presently. The Bureau of Mines, U.S. Department of the Interior, has been conducting research on the chalcopyrite to produce a marketable fraction enriched in cobalt and nickel. Ferric chloride leaching of various chalcopyrite (copper) concentrates has yielded residues containing from 10.2 to 16.2 pct Ni and 8.3 to 11.4 pct Co with recoveries of approximately 79 pct. In another approach, laboratory froth-flotation tests have been conducted to investigate the effects of regrinding, roasting, baking, and steaming prior to flotation, with a variety of reagents. The best laboratory results were obtained after regrinding the copper concentrate to 94 pct minus 400 mesh and floating the chalcopyrite at natural pH (6.5) with 0.48 pound of sodium diethyldithiophosphate and 0.01 pound of sodium cyanide per ton of concentrate. This procedure yielded a tailings assaying 20.4 pct Cu, 5.2 pct Ni, and 3.45 pct Co. The tailings contained 67.2 pct of the nickel and cobalt and 15.9 pct of the copper originally in the copper concentrate; the remainder of the values reported to the flotation concentrate, which analyzed 29.6 pct Cu. To verify the laboratory flotation results, a 60 kg/hr process demonstration unit (PDU) was constructed in the Cominco American Magmont mill, Bixby, Mo.

Jan 1, 1978

By H. H. Dewing

The Bureau of Mines conducted a laboratory-scale investigation of a technique that produces zinc sulfate and elemental sulfur from sphalerite concentrates by reaction with sulfuric acid at 175° to 200° C and ambient pressure. The objective of the investigation was to develop a hydrometallurgical method of producing zinc from sulfide concentrates that does not generate sulfur dioxide pollutants. Reaction with 80-to 85-pct sulfuric acid produced 4 moles of sulfur for every 3 moles of sphalerite reacted, with minimal production of sulfur gases under optimum conditions. More than 98 pct of the zinc was recovered as zinc sulfate after 3 hours at 175° C. The reaction mixture was leached with simulated spent zinc electrolyte containing 13-pct sulfuric acid to recover zinc sulfate from the insoluble, high-sulfur residue. Neutral zinc sulfate, which is required for electrolysis, was separated from the sulfuric acid solution by crystallization as ZnS04?7H20 at -10° C. Up to 80 pct of the water in the recycled electrolysis solution was removed by the crystallization process; evaporation was used to further concentrate the sulfuric acid for reuse in leaching sphalerite. Advantages of the proposed method over conven-tional roasting and leaching include virtual elimination of sulfur dioxide, production of a solid sulfur byproduct, and higher zinc recoveries due to elimination of zinc ferrite losses.

Jan 1, 1978

By J. H. Perry, Joseph Cervik, G. N. Aul

The Bureau of Mines is conducting research to determine the effectiveness of long holes in degasifying an area of the Upper Split of the Lower Sunnyside coalbed at Kaiser Steel CO.&apos;s Sunnyside No. 1 mine. These holes were drilled from the two outside entries of a section that was closed to mining because of excessive methane emissions. Two holes drilled to 430 and 450 feet produced initial gas flows of 160,000 and 127,000 cfd, respectively. Sixteen days after the completion of the second hole, the total gas production declined to just over 144,000 cfd. In 9 months of degasification, over 35 MMcf of commercial-quality gas has been removed from the coalbed. The combined gas flows declined to 106,000 cfd in the 9-month period. The two holes have reduced face emissions by about 40 pct.

Jan 1, 1978

By J. H. Perry

The Bureau of Mines is conducting research to determine the effectiveness of long holes in degasifying an area of the Upper Split of the Lower Sunnyside coalbed at Kaiser Steel Co.&apos;s Sunnyside No.1 mine. These holes were drilled from the two outside entries of a section that was closed to mining because of excessive methane emissions. Two holes drilled to 430 and 450 feet produced initial gas flows of 160,000 and 127,000 cfd, respectively. Sixteen days after the completion of the second hole, the total gas production declined to just over 144,000 cfd. In 9 months of degasification, over 35 MMcf of commercial-quality gas has been removed from the coalbed. The combined gas flows declined to 106,000 cfd in the 9-month period. The two holes have reduced face emissions by about 40 pet.

Jan 1, 1978

By J. E. Matta

The Bureau of Mines has developed a tracer gas method for measuring leak-age through permanent mine stoppings. In this method, a temporary brattice is erected in the same entry as the leaking permanent stopping. Leakage was evaluated from concentration measurements of a tracer gas introduced into the space between the stopping and brattice. Stopping leakages ranging from 15 cfm to 265 cfm were simulated in an underground coal mine. Leakage values determined by the new method were within 10 pct of the known values.

Jan 1, 1978

By A. F. Colombo

In an effort to maintain an adequate supply of iron to meet national economic and strategic needs, the Bureau of Mines, U.S. Department of the Interior, is conducting research on methods for beneficiating the oxidized taconite resources located on the western Mesabi range in Minnesota, thus expanding domestic iron ore reserves. The selective flocculation and cationic flotation process was investigated in a pilot plant using an ore feed rate of 410 kg/hr (900 1b/hr) and 88 percent recycled water. Lime and a cationic flocculant were used to clarify the waste slurries treated in the water reclamation circuit. An oxidized taconite assaying approximately 36 percent Fe yielded concentrates averaging 63.5 percent Fe and 4.3 percent SiO2 and having an average iron recovery of 84.4 percent. The estimated reagent cost per tonne of concentrate was approximately $1.10. In an attempt to recover more of the iron lost in the flotation tailing, wet high-intensity magnetic (WHIM) separation was incorporated in the pilot plant circuit. The flotation concentrate grades obtained from beneficiation circuits with and without WHIM scavenging were similar, but when WHIM separation was used the overall iron recovery was increased by 2 to 9.5 percent, depending on the iron assay of the flotation tailing.

Jan 1, 1978

By J. C. White

A research study was conducted to devise a method for producing phosphoric acid directly from unbeneficiated Florida phosphate matrix. This research was performed as part of the Bureau of Mines, U.S. Department of the Interior, goals of improving minerals and metals recovery from domestic resources and of minimizing the environmental impact associated with mineral recovery operations. This report describes research in which unbeneficiated, dry, south-central Florida phosphate matrix was digested with sulfuric acid in a continuous-circuit, five-tank reactor to yield phosphoric acid and gypsum residue. Feed capacity of the reactor was 100 pounds (45 kg) of dry matrix per 24-hour day. When digestion was carried out at 185° F (85° C), acid filtration rates of up to 420 pounds of P20S per square foot per day were attained. Combined iron and aluminum impurities in the product filter acid were about 60 percent greater than values reported in commercially produced acid derived from concentrate. phosphate recovery was 87 to 90 percent of the phosphate contained in the as-mined matrix.

Jan 1, 1978