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By Alfred F. Savage

The Oglebay Norton Company has traditionally been a supplier of metallurgical grade fluorspar gravel to the American steel industry and, in the early sixties, fluorspar pellets were entered into the market. The gravel has been imported from Mexico, the pellets were produced by the Minerva Company in southern Illinois. While the acceptance of the pellets by the industry was satisfactory, overall marketing considerations caused the Minerva Company to discontinue the pelletizing operations. Thus it was that Oglebay Norton came to the decision to revive earlier plans to produce fluorspar agglomerates. A survey of the market and related factors led into two basic conclusions: 1) Because of steel plant safety considerations, flat, pillow- shaped briquets were preferable to easily rolling, marble-like pellets. 2) Briquets competitive with gravel could be produced by cutting imported, low-duty, acid grade spar to metallurgical grade by limestone and binders. A plant was built in Brownsville, Texas, and started operations in early 1970.

Jan 1, 1975

By T. Carageorgos

The removal of arsenic from process streams as ferric arsenate compounds is being practised by mining industries. Therefore, the solubility and stability of these solids is of considerable importance to the mining plants that have to keep the environment free from pollutants. There is some information on the solubility of the ferric arsenate compounds, mainly on scorodite, obtained from synthetic solution. However, there is not so much work on ferric arsenate compounds formed at high temperatures (175 - 230°C) during the leaching process. In the present work, the solubility of the ferric arsenate compounds formed during acidic pressure oxidation of arsenopyrite is presented. The results of the solubility tests showed that the ferric arsenate compounds formed at high temperatures (200 - 230°C) and high pressures (1034 - 1551 kPa 0,) released arsenic into solution in amounts less than 1.2 ppm and iron in amounts no higher than 1.0 ppm. So, they seem to be potential compounds for arsenic and iron disposal.

Jan 1, 1998

By Fathi Habashi

METALS COMMONLY leached may come from one of the following sources: 1) Occurring in nature in the native state, e.g., gold, silver, platinum metals, copper. 2) Produced as by-product of a metallurgical process, e.g., gold, silver, platinum metals, selenium. 3) Produced by reduction of an oxide ore, e.g., copper, nickel. GOLD AND SILVER Cyanidation According to Mellor (1923) the alchemists of the eighteenth century knew that gold was soluble in aqueous solution of potassium cyanide, and the early jewelers probably utilized this fact in gilding. He also mentions that Scheele in 1783 and later Bagration in 1843 noted the solvent action of aqueous solutions of alkali cyanides on gold. Yet it was not until 1887 that the value of this observation was recognized, when MacArthur and Forrest (1887) made use of it in leaching gold from its ores. Since then, the process has spread to every gold and silver mining district in the world.

Jan 1, 1970

By Michael Li

Unsaturated flow and solute transport were studied in three large columns measuring 1.5 m diameter x 2 m height, loaded with up to 3.7 t of oxidised waste rock, which was excavated from the Stratmat pile at Heath Steele Division, Noranda Inc. and contained elevated concentrations of zinc in the pore water. The bottom of each column was partitioned into 37 squares, each of which was drained independently. Following rain simulations at the top of the rock bed, the drainage in each drain port was monitored for volume and physicochemical parameters at pre-determined intervals. This paper describes some of the observations resulting from the experiments. The main conclusion of the study is that unsaturated flows in waste rock are heterogeneous, and flow channelling is ubiquitous. The results imply that the transport of solutes from oxidised waste rock to its toe drainage is subject to various controlling mechanisms, including geochemical equilibrium control and successive pore water dilution control.

Jan 1, 2000

By A. Ardiant, C. E. F. Mumbunan, I. Irawan

As a part of mine operation’s success key, Community Development nowadays seems to be a rule of thumb. Not only is for a short term need of the company during their operation but also for the national public opinion on the presence of the mining industry to a certain region. Nanggung region which is only a 2-hour drive from Jakarta, brings the challenges to Antam’s gold mine business in the areas such as illegal miner presence, easy access to the mine area as it is very close to the community, and national political sensitivity considering its proximity to Jakarta. The company allocates about 3%of its total operational cost annually for Community Development pro-gram. The program is derived through SWOT analysis and broad involvement of all community components to assure that the allocated fund is addressed to the right place. In the year of 2002, the company has successfully established a conducive-relation with the community.

Jan 1, 2004

By L. Hagenbuch

Off-highway truck purchasers know the amount of tonnes, pounds, kilograms, etc, a truck will carry. However just because a truck is rated at 240 tons may in no way correlate to what that truck will actually carry. Two numbers define the carrying capacity of an off-highway truck: 1. The weight carrying capacity of the truck; 2. The volume carrying capacity of the truck. These two numbers must be in sync or the amount of payload carried will vary from the carrying capacity of the truck. Currently the Society of Automotive Engineers (SAE) standard J1363 January 1985 defines the volumetric carrying capacity of an off-highway truck. However as is well known in several South American countries, the SAE standard overrates the truck’s effective volumetric carrying capacity 15% to 20%. This paper presents a method for measuring “effective” body volumetric carrying capacity, resulting in a truck body for carrying the targeted load, matched to the loading equipment that interacts positively with the truck chassis.

Jan 1, 2002

By Scott G. Britton

Many times during the construction of a project, whether large or small, the engineer will become involved with management of the work and workforce. In some cases, mine management will turn over the direction and responsibility of doing the work to the engineer. Because of this, it is important to know some of the basic principles of human resource applications- among other management concerns. This chapter, therefore, looks at the fundamental principles of human resource management. Three broad discussions are presented to the reader. These are: (1) organization, communications, and responsibilities of management; (2) analysis of worker motivation; and (3) supervisory leadership. Each topic encompasses the current thinking for coal mining and mining management. Much of the information in this chapter comes from Practical Coal Mine Management, by this author and published by John Wiley & Sons, Inc., which discusses in depth many of the ideas presented here. Interested persons are directed to this text for more information on management skills.

Jan 1, 1983

By D. A. Newman

A longwall chain pillar is comprised of two distinct zones, a solid elastic core enclosed by an exterior of failed or yielded coal. For the purpose of pillar design, the ability to delineate the extent of pillar yielding and correlate the yielding with the applied pillar load is of fundamental importance. A study was initiated on a longwall section of a West Virginia mine to: (1) delineate the location of the elastic core-yield zone boundary, (2) examine the stress distribution within the pillar, and (3) quantify pillar stability as the longwall face retreated toward an instrumented pillar. A US Bureau of Mines sonic velocity probe was used in conjunction with vibrating wire stress meters to define the elastic core-yield zone boundary and the migration of vertical stress toward the pillar core. The extent of the yield zone as determined by field results is compared with the extent of the failed zone as predicted using a series of equations developed by Wilson.

Jan 1, 1988

By Thomas A. Wheeler, Robert O. Keys

The choice of the flotation reagent that suits a particular coal has become more complicated with the development of new, more efficient reagents. Frothers and conditioning reagents, in particular, have experienced a dramatic reevaluation of their role in floating various types of coals. This paper offers a better understanding of how each of the following factors contributes to the reagent selection: 1. Natural Flotability 2. Degree of Oxidation 3. Size Distribution 4. Percent Solids in Feed Slurry 5. Fluctuations in Plant Feed 6. Limitations on Froth Handling 7. Clean Coal Specifications 8. Ash Content in Feed a) discrete ashable minerals b) inherent ashable minerals 9. Water Chemistry 10. Petrographic Composition of Coal 11. Free-Swelling Index 12. Convictions of Customer The application of conditioning reagents - both promoters and emulsifiers can substantially improve the coal recovery. Some low-rank, hydrophylic coal, previously considered unfloatable can be economically recovered with the use of the proper reagent.

Jan 1, 1986

By M. Elzeky, A. Attia

The effects of bacterial adaptation and partial replacement of leaching solution on the rate and extent of bioleaching reactions of a complex sulfidic gold ore were investigated. The ore was first concentrated by bulk sulfide flotation and the sulfide concentrate was treated by bioleaching using T. Ferrooxidans bacteria. The residues from bioleaching were treated by cyanidation to extract the gold and silver. Bacterial adaptation before bioleaching significantly increased the rate and extent of bioleaching reactions. Similarly, the daily partial replacement of leaching liquor enhanced to a great extent the leaching rate and in some cases up to ten fold increase was observed. Both bacterial adaptation and solution replacement increased the gold recovery by about 2-fold and that of silver by about 1.3-fold. In this work more than 95% of the gold and more than 98% of the silver could be recovered from the sulfidic gold ore, when bioleaching was used ahead of cyanidation compared with 18.3% and 52.3% by direct cyanidation.

Jan 1, 1989

By S. Chander, A. Briceno

The properties of surface films on pyrite have been studied through electrochemical techniques of cyclic voltammetry and AC impedance, measurements. The characteristics of the surface films depend on the conditions of oxidation and the source of pyrite. At potentials near 0.0 V, some pyrites have large values of polarization resistance, showing a certain degree of passivity. Some pyrites show more passivation than others, however. On oxidation, meta- stable phases of Fe(OH)2 and Fe(OH)3 form that transform to more stable phases on aging. The growth of surface films near the corrosion potential of pyrite follows a linear kinetics that is attributed to a chemical (or an electrochemical) reaction as the rate determining step. The surface film is considered to be a hydroxide or an oxide because it is hydrophilic. This study has also demonstrated that AC impedance ,measurements can be used to study the growth characteristics of films at mineral/solution interfaces.

Jan 1, 1988

By S. A. Moffatt

For several years iron ore processing plants, located in the northern U.S. experienced seasonal decreases in the grinding efficiency of their primary autogenous mills. Kawatra and Eisele (1992) studied this phenomenon in an operating plant and characterized it in terms of specific energy consumption (Fig. 1) and production of critical size material (Fig. 2). Critical size material is defined as ore that is too small to be effective grinding media and too large to be ground. This data showed that both specific energy consumption and critical size production increased during the winter months. The increased energy consumption was in part a result of an increase in the viscosity of the mill pulp at colder pulp temperatures. However, viscosity could not fully explain the changes in critical size production. These changes are most likely due to changes in the breakage characteristics of the ore. Other studies were also conducted to determine if thermal and physical properties of iron ore changed at colder temperatures. These are summarized below:

Jan 1, 1993

The Peruvian mining industry has seen an explosion of foreign investment since President Albert? Fujimori's government was first elected in 1990. Since then, Peru has taken some large steps toward recovery, making it the envy of most other developing countries. A measure of political stability was gained in 1992 when Shining Path leader Abimael Guzman was captured. In addition, the country has taken on a huge privatization program, rewritten its foreign investment laws and has reined in its annual inflation rate from 1,700% in 1990 to about 8% by late 1997. Small wonder then that attendance at the XXIII Peruvian Institute of Mining Engineers conference reached a record level, many of whom are employed by some of the world's largest mining companies. About 2,700 mining industry professionals from all over the world attended the week-long event, held in late September in Arequipa. That was an increase from 1995s 1,600 attendees, that meeting also held in Arequipa.

Jan 1, 1998

By George A. Desborough, Stephen J. Sutley, Reinhard W. Leinz, Paul H. Briggs

The mode of occurrence of metals in mine wastes is investigated using sequential extractions. Metals are extracted from some or all of seven operationally-defined phases: water-soluble, ion-exchangeable, carbonate, amorphous Fe-oxide, crystalline Fe-oxide, sulfide, and silicate. The quantity of metals extracted from each phase varies with particle size. The presence of jarosite (potassium end-member formula, KFe3[SO4]2[OH]6) influences the selection of the procedure for extracting the crystalline Fe-oxide phase. Anglesite (PbSO4) and cerussite (PbCO3) are extracted as several phases. Extraction results can be explained only in part by X-ray diffraction (XRD) mineralogy because of lack of specificity of the extraction procedures, relatively high XRD detection limits, and the presence of 40% XRD-amorphous matter in each waste. The increasing chemical strength of the sequentially applied methods provides a basis for judging metal availability, water-soluble metals being most available and silicate-bound metals being least available.

Jan 1, 2000

By P. D. Rao, D. E. Walsh

A pilot-scale study was performed to evaluate the potential for gravity concentration of gold from -13 mm (-1/2 in.) crushed ore from Ester Dome, AK. 9.04 t (9.94 st) of crushed ore were sampled and processed through a Pan-American jig-Wilfley table pilot plant. Plant products were sampled for assay and material balance calculations. Gold recovery through one stage of jigging and two stages of tabling was 17.4% at a concentration ratio of 615:1. Concentrate grade was 766.3 g/t (22.4 oz/st). The feed grade to the plant was calculated at 1.71 g/t (0.05 oz/st). Jig tailings, primary table tailings and secondary table tailings grades were 1.44 g/t (0.042 oz/st), 1.30 g/t (0.038 oz/st), and 5.47 g/t (0.16 oz/st, respectively. Significant coarse, free-milling gold values were shown to remain in the, jig tailings. Concentrate mineralogy is discussed.

Jan 1, 1992

By Travis S. Wellman, Jon C. Volkwein

The Bureau of Mines conducted a study to assess the impact of a directional water spray system on a unique single inlet dust scrubber on a low profile mining machine. Tests were conducted in a full scale model mine using a Joy 12 CM 10-AA continuous mining machine. Tracer gas was introduced at the face and concentrations of the tracer gas were monitored at the face and in the return. Various parameters included: mining position, depth of cut, brattice setback and combinations of scrubber, directional sprays or symmetrical sprays. Results indicated that either directional or symmetrical water spray configuration improved the ventilation effectiveness of the scrubber by a factor of 2 to 3. Average face ventilation effectiveness (FVE) values for all testing of the scrubber and directional sprays were 0.95, versus 0.37 for a standard 6 m (20-ft) blowing curtain without sprays. No FVE values were less than the standard 6 m (20-ft) blowing results.

Jan 1, 1989

By C. J. Hall

An investigation of multi-shaft airflow problems by the author in 1976 (1) was presented in the hope of arousing considerable written comment, but in fact-. only one contribution (2) was forthcoming. The investigation in this paper is taken several stages fur¬ther, because the matter is of major importance in many American hard rock mines with complex networks extending over thousands of meters vertically. The examples used have all been generated thermodynamical¬ly and checked by motive column (denisty) calculations. Dry air has been used to reduce the amount of time spent on the rather complex calculations, but it has been shown (3) that the principals developed apply equally well to air/vapor/water mixtures. Initially the subject is investigated using both thermodynamic and motive column analyses. The latter part of the paper concentrates on a motive column presentation. Both methods are, of course, equally valid and give identical answers to any situation when correctly applied, as is shown in the worked examples.

Jan 1, 1980

By D. D. Runnells, D. C. Keith, G. A. Doyle, J. Tilk

Until the suspension of conventional operations in 1996, the White Pine Mine was the second-largest active underground copper mine in the United States, underlying an area of approximately 30 km2 (13 sq. miles) in the Upper Peninsula of Michigan. The mine operator intends to initiate in-stope solution copper mining by circulating a solution (lixiviant) of mine water, sulfuric acid and ferric iron through rubblized ore. As planned, the solution would be retired in the mined-out stopes following completion of the solution-mining activities. Investigations into the fate of the retired solution indicated that the solution, through time, would change from an acidic, metal-rich solution to a near-neutral, reducing solution containing much lower concentrations of metals. Investigations included reaction-path modeling (EQ3/6) and laboratory and in-mine tests. The combination of neutralization and reduction will result in precipitation of most metals, primarily as metallic sulfates, chlorides and sulfides.

Jan 1, 1998

By Y. A. Attia, M. Elzeky

The effects of bacterial adaptation and partial replacement of leaching solution on the rate and extent of bioleaching reactions of a complex sulfidic gold ore were investigated. The ore was first concentrated by bulk sulfide, flotation, and the sulfide concentrate was treated by bioleaching using Thiobacillus ferrooxidans. The residues from bioleaching were treated by cyanidation to extract the gold and silver. Bacterial adaptation before bioleaching significantly increased the rate and extent of bioleaching reactions. Similarly, the daily partial replacement of leaching liquor enhanced to a great extent the leaching rate, and in some cases, increases of up to ten fold were observed. Both bacterial adaptation and solution replacement increased the gold recovery by about 2-fold and that of silver by about 1.3-fold. In this work, more than 95% of the gold and more than 98% of the silver could be recovered from the sulfidic gold ore when bioleaching was used ahead of cyanidation, compared with 18.3% and 52.3% by direct cyanidation.

Jan 1, 1992

By M. A. Greenwood

The total value of coal, FOB mine, consumed in the United States was $21 billion in 1985. Roughly $6 billion was spent to transport coal from the mine to the consumer by rail. This indicates the impact railroad transportation has on the competitiveness of U.S. coal as an energy resource. Actually, this is just the tip of the iceberg. When you consider the largest U.S. reserve of coal, the Powder River Basin, which is possibly the lowest cost coal in the U.S., or maybe even the world, the transportation cost is the overriding factor in developing competitive pricing. Rail transportation costs from Powder River can be multiples of 2, 3, or even 4 times the cost of coal FOB mine. About sixty percent of all U.S. coal is shipped by rail. In the case of Powder River Basin coal and many other reserves there are no current alternatives to rail. Are there feasible alternatives to rail transport?

Jan 1, 1986