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By A. Yehia

Fluoride activation has been evaluated by Hallimond-tube flotation of collophanite in terms of fluoride concentration, conditioning time, pH, and temperature. The results reveal that efficient oleate flotation of collophanite can be achieved by fluoride activation. Fluoride adsorption by collophanite as a function of fluoride concentration, temperature, pH, and crystal structure suggests that, at low fluoride concentration, a fluoroapatite-type compound may form on the collophanite surface by chemisorption of fluoride ions at calcium sites; at high fluoride concentration, calcium fluoride ap¬pears to form at the collophanite surface invovling a surface-precipitation phenomenon. The formation of CaF2 on the surface of fluoride-treated collophanite is further substantiated by the FTIR spectroscopic measurements, which clearly shows a metathetic exchange with phosphate from the collophanite lattice during surface precipitation process.

Jan 1, 1986

By Fiona M. Doyle Garner

Hydrolytic stripping is the process whereby metal ions in a loaded solvent extractant are hydrolyzed by water, typically at 130°-200°C. Equilibrium hydrolytic stripping tests were done on Versatic 10 solutions of various metals, singly and in mixtures. Single solutions of Fe, Xi, Cu, Mg, and tin precipitated aFe2O3, Ni(OH)2, Cu2O, Mg(OH) 2 and ?Mn203 respectively during hydrolytic stripping. Several mixtures containing iron precipitated magnetic spinel ferrites, MFe20k. No other combinations formed mixed oxides. It is proposed that the mechanisms for hydrolysis and precipitation of iron in loaded Versa- tic solutions are similar to those for iron hydrolysis in aqueous solutions. Infrared spec- troscopy and thin-layer chromatography of mixed iron-nickel Versatic solutions indicated that mixed Fe-Ni carboxylate complexes are present. Magnetic interactions between mixed complexes are thought to be responsible for the homogeneous nucleation of magnetic mixed oxides in preference to single oxides.

Jan 1, 1984

By J. N. Hartley

Uranium mill tailings, waste products of uranium extraction, contain hazardous constituents that if released into the atmosphere and groundwater could threaten our health and environment. To provide for safe disposal and control of these tailings, Congress enacted the Uranium Mill Tailings Radiation Control Act of 1978 (Public Law 95-604). Subsequently, the Environmental Protection Agency (EPA) established standards for tailings disposal that limit radon emission into the air to 20 pCi m-2s-1 on an annual average basis (EPA 1983). The design life of the impoundment is to be 1000 years where practicable, but 200 years at least. To facilitate the design of containment systems that will meet the EPA standards, the Nuclear Regulatory Commission (NRC) and the Department of Energy (DOE) are sponsoring research at the Pacific Northwest Laboratory (PNL)* to develop the necessary technology. Earthen and asphalt materials have been evaluated for use as radon barriers (Hartley 1983) and as liners to minimize leaching (Buelt 1983). Herbicide and rock barriers against biological intrusion have been evaluated (Cline 1982). Surface stabilization techniques have been investigated to maintain the long-term effectiveness of a containment system that must be protected from wind and water erosion, chemical and physical degradation, and biological disturbance.

Jan 1, 1984

By K. H. Boss

In modern iron pelletizing plants fuel consumption has been optimized to such an extent that only minor savings can be expected in the future. Inspite of this fact, different process parameters were studied with a mathematical model and firing tests. The influence on fuel consumption and productivity was established. Furthermore, the adoption of simplified firing patterns was investigated, in particular for coal firing. In view of high costs of oil and natural gas, only substitution of these fuels by coal can substantially reduce production costs. In existing plants partial replacement of oil and gas can be achieved by addition of coal to the iron ore feed and by firing the pellets with pulverized coal. Two systems have been developed for the Lurgi- Dravo travelling grate process which enables coal to completely replace oil or gas. This paper describes in the first part the potentials for fuel savings available in the Lurgi-Dravo process. In the second part, different techniques for the use of coal as fuel in iron or pelletizing plants and in particular the recently developed Lurgi Multistage Coal Injection and Combustion Process (LMC) are discussed. Combined with the LMC process, a wide variety of iron ores and coals - also with high ash contents - can be used in the Lurgi-Dravo travelling grate process.

Jan 1, 1983

By R. H. W. Chadwick

We in Kennecott are well aware that Alaskans are interested in the progress of our project at Ruby Creek. We would very much like to be able to present you with a final report at this time and tell you about a new mine. I'm afraid, however, that it will be several years at best before such a report can be made. This, then, is an interim report to describe briefly some of our findings to date, and to acquaint you with some of the problems, both geologic and economic, which must 5e resolved favorably before we can talk about a mine. There are several things about this project which make it unusual and interesting to those of us who have been connected with it. Firstly, there is the fundamental importance to Alaska, in the present stage of its economic history, of any undertaking which offers promise of turning a natural resource into a competitive export product. I am sure all of us would get a lot more satisfaction out of having a part in bringing in a new mine in Alaska than we would out of adding another one to the long list in, say, Arizona.

Jan 1, 1960

By M. A. A. de Klaver

Due to the current cost and availability of crude oil in Brazil, Samarco Mineracao S. A., as part of its program of quality and productivity optimization and reduction of operating costs, has undertaken tests to utilize alternate energy sources for fuel oil used in its pelletizing plant at Point Ubu, Espirito Santo, Brazil. The energy program undertaken by Samarco consists of two basic steps. The first step was to reduce energy consumption, that is, to improve the thermal efficiency of the process. Secondly, a program was started to substitute the fuel oil with coal.

Jan 1, 1984

By T. Kelly

The Cannon Mine is located in Chelan County, near Wenatchee, Washington, at the eastern foot of the Cascade Mountains. The mine is situated about two miles from the Columbia River, in the arid Columbia River Valley. Two hydroelectric dams provide electricity for the area, the Burlington Northern Railroad has a switch yard and loading facilities in Wenatchee. Approximately 25,000 people live in the area. The principal industry is fruit farming. Underground mining techniques are used to provide feed for a 2,000 tpd flotation concentrator at the site. The techniques are low- cost, high productivity methods which allow for a high extraction rate along with a high rate of recovery of the minable reserve.

Jan 1, 1986

By T. G. Rozgonyi

The basic goal of this investigation was to determine the degree of drying of high moisture lignite through the use of high temperature and pressure steam autoclaves. Specific items studied were: a) the effect of lignite particle size, b) steam temperature and pressure required, and c) the time of ahydration. Although removal of sodium, ash, sulfur and other ash-forming minerals was not the goal of this study, basic analysis of effluent water showed organic material and alkalai metal content. Removal of inherent moisture from run-of-mine lignite was tested by lock-feeding the lignite, which was previously sized by screening into 25 kg autoclaves. High pressure, up to 4.053 MPa (588 psi), saturated steam was then introduced into the pressure reactor. Reaction time, pressure, temperature, and depressurization rates were strictly controlled for each reactor test run. Results indicate that about 80% of lignite total moisture was removed, including some of the inherent moisture, yielding a non-oxidized, and thus stable, lignite product. As stated, a side benefit occurred as some reduction of non-combustible portions of the lignite also took place. The conclusion reached as a result of the tests is that the steam-drying process can be successfully applied to reducing moisture in lignite, and may be considered for additional studies on acceleration of the coalification process. On the basis of the data presented, the author believes that lignite can be economically upgraded in steam autoclaves by simultaneously reducing the moisture content by 80 percent and the sulfur content by at least 50 percent. Upgrading the lignite by this method will result in large energy and financial savings.

Jan 1, 1984

By David Burgess

The paper describes experiments at the Somerset Mine, Colorado, under a cooperative agreement between U.S. Steel and the U.S. Bureau of Mines. A test was made of the tube bundle method of mine air sampling which was developed for European longwall mines; some 300,000 running feet of tubing provided continuous monitoring at 39 locations. Carbon monoxide concentrations were obtained with standard deviations of less than 1 ppm and oxygen concentrations with standard deviations of less than 0.20 percent. A base level of CO index (ppm CO evolved/pct 02 removed)) was determined to be 0-20 through most of the passageways of the mine. However, in one working section where the coal was initially hot (about 180°F within a pillar) the CO index was demonstrably higher, >20 trending upward to about 60 when smoke appeared and the section was sealed. The data are discussed in terms of laboratory experiments on CO evolution from coals.

Jan 1, 1975

By William E. Lamont

The Mineral Resources Institute (MRI) of the School of Mines and Energy Development (SOMED), University of Alabama conducted studies to determine the potential for upgrading the Eastern Devonian shales by flotation. Results of those studies indicate that flotation concentrates containing 150 liters of oil/t (36 gal/t) can be produced from shale containing 50 liters of oil/t (12 gal/t) as determined by Fischer Assay with good recovery of the kerogen. Organic carbon and trace elements such as molybdenum, vanadium and uranium also are concentrated with the kerogen. Kerogen concentration was found to be a function of the size of grind.

Jan 1, 1983

By J. B. Hiskey

Thiourea is a reagent capable of complexing gold and silver. With the proper oxidant, thiourea can effectively dissolve metallic gold and silver. A thiourea leaching system possesses potential advantages over conventional cyanidation including acidic solutions instead of alkaline, cationic complexes in contrast to metal-cyanide anionic complexes, and faster leaching rates with acidic solution of thiourea. Generally, the rate of metal dissolution in thiourea solutions is fastest when ferric ion is employed as an oxidant. Acidic thiourea solutions for certain applications could offer a nontoxic and noncorrosive option for processing gold and silver. This paper provides information regarding the fundamental chemistry of the acidic thiourea system, and reviews the dissolution of both silver and gold in acidic solutions of thiourea. The recovery of gold and silver from acidic thiourea solution is discussed.

Jan 1, 1981

By Nathaniel Arbiter

After almost 60 years of application in this country froth flotation is still by far the most important process for concentrating metallic ores as well as a number of nonmetallic ores including fluorspar, phosphate rock, and potash. Its use on iron ores and coal is increasing. In the metals groups the largest plants and the greatest progress are found in copper and molybdenum mills, and the section of this paper that deals with applications will be found most pertinent to that field. During its long reign the flotation process has passed through several phases of evolution and has achieved progress in economy, efficiency, and simplicity of operation. Much of today's success in the flotation of low-grade ores can be attributed to that progress. Even more important to us than our ability to cope with today's conditions are tomorrow's problems, which we can contemplate with some prescience and confidence. Our annual production of copper, lead, zinc, and molybdenum--to mention only the most important metals occurring in the U.S. as sulphides--must be held at a high level in the face of a declining grade of ore. It is probable that the tonnage of such ores mined and processed will double in this country before the turn of the century. Not only will many of the existing flotation mills be enlarged again and again, but larger mills will be built here and abroad to meet our needs. At this moment, in fact, there are at least three proposed new foreign mills or expansions that envision 100,000 tons daily milling rate on copper ores. Table I (1) shows the trend in copper ore grades in U.S. in recent years:

Jan 1, 1970

By Dermot M. Ross-Brown

The objectives of this generic study were to use numerical modeling techniques to determine under what conditions seismic waves generated by an earthquake might cause instability to an underground opening, or cause fracturing and joint movement that would lead to an increase in the permeability of the rock mass. In general, the study showed that moderate earthquakes (up to 0.41 g) did not cause instability of the tunnel or major fracturing of the rock mass. An artificial rock-burst tremor with high accelerations, however, was found to be amplified around the tunnel, and fracturing occurred as a result of the seismic loading in salt and granite. In shale, even moderate seismic loading resulted in tunnel collapse.

Jan 1, 1981

By J. H. Wilhelm

Continuous thickeners can be sized either from previous experience, continuous pilot-scale test results, or from batch settling tests. Although it is a relatively simple process to size full-scale thickeners when previous experience or pilot-scale operating data are available, batch testing is often the only realistic method for sizing thickeners due to time restrictions, budget limitations and availability of sample material. Many authors have, therefore, suggested means of running batch tests and analyzing the resulting data. Fundamental thickening theory had its beginning with the work o£ Coe and Clevenger(1). In order to determine the size of the thickener settling area, they proposed that a series of batch settling tests be run at various initial concentrations. The solids handling capacity at each concentration can then be determined and the lowest capacity (maximum area requirements) used to size the thickener. Kynch(2) developed a mathematical analysis in which the relationship between solids concentration and settling rate can be obtained from a single batch settling curve. Talmage and Fitch(3), Yoshioka(4)(5) and Dick(6), have enlarged upon these works to give a basis for methods of sizing thickeners.

Jan 1, 1979

By G. M. Clarke

Minerals are certainly where they are found. The undemocratic distribution of the world's mineral wealth has created an incongruous inbalance: mineral-rich, scarcely populated countries supply highly-populated industrialised countries that in turn consume more minerals than they produce. This has been as much a generating force for colonisation, invasion, and war as religion, political ideals, or megalomania. The Industrial Revolution of the seventeenth century was born in Britain, a country with large domestic resources of coal, iron, lead, zinc, copper, tin, etc., as well as a large population. As consumption outstripped production imports filled the gap, particularly from its worldwide colonies. For example, when Canada was founded in 1867 more than 905 of its investments were British financed, and much of these were mineral-based. The British made similar investments in South East Asia, Australasia, the Caribbean, and elsewhere, as did the other industrialised Western European countries hungry for raw materials. Later the United States emerged as a leading industrial power, again due largely to its abundant natural resources. Consumption soon exceeded production and foreign sources were saught. American business went exploring abroad ant many a mineral resource was developed almost totally on the basis of the US market many .thousands of miles away. Closer to home, Canada was also an obvious target for the US with its rich mineral resource base, small population, and geographical juxtaposition, so much so that about the time of the 1914-18 War the US took over from Britain as the major investor in Canada, and this peaked in 1967 when the US accounted for 80% of the country's foreign investment. After the 1939-45 War Japan joined the ranks of the USA and Western Europe as industrialised powers, and they too searched the world for the deposits lacking in their homeland.

Jan 1, 1981

By Jr. Koch

Since 1882, world zinc production has increased. In contrast, United States zinc production rose until about 1915, but since then has remained nearly constant, with a slight tendency to decrease. Production from the Tri-State district, the largest early source of zinc in the United States, has gone down steadily; this decline has been balanced by a growth in the rate of other districts. These changes in United States production are due to economic, not geological, factors. Recent exploration has located large mineable ore bodies; additional deposits will undoubtedly be found in the strata-bound carbonate rock and volcanogenic environments. A statistical analysis of the exploration effort in the Middle Tennessee district indicates that new discoveries can be expected there. Thus, the United States is in an early stage of the production cycle for zinc. Of major mining districts in the United States, only the Tri-State is exhausted under current economic conditions; large zinc resources of low-grade material, which would repay mining at higher prices or improved technology, are known to exist in that district.

Jan 1, 1980

By Katerina Adam

During wet grinding the electrochemical interactions between grinding media and pyrrhotite not only accelerate the media wear but also adversely affect the flotation response of the sulfide mineral. A possibility of remedying the adverse effect on its floatability by applying electric potentials to grinding media was examined. Flotation tests, Auger electron spectroscopy and x-ray photoelectron spectroscopy were used to study the surface properties of pyrrhotite. Although anodic polarization of the steels increased the metal loss by corrosion, the flotation recovery of pyrrhotite was increased. In the case of cathodic polarization, the flotation recovery improved in a narrow range of overpotentials. At higher cathodic overpotentials, however, the floatability of the mineral was progressively lowered although the corrosive wear of grinding media might be reduced.

Jan 1, 1984

By Yoginder P. Chugh

Physical mine modeling and computer simulation techniques were used to conduct technical feasibility and economic analyses of selected pit configurations for surface mining a single coal seam dipping at about 15 percent to a maximum depth of 150 feet. The pit orientations along the dip (dipline), strike (strikeline) and along an apparent dip were studied. Physical models of each pit configuration were prepared first to delineate potential operational problem areas, and also to furnish a data base-for the computer simulation models. A dragline micro- simulation model (Fluor), a shovel/truck simulation model and a cost analysis model were used to conduct the study. Sensitivity analyses were conducted on variables such as the pit width, block length, and angle of dip. The productivity (Cu.yds/hour) of the mining equipment (dragline or stripping shovel) under each set of conditions was used to optimize the pit configuration. Both block length and panel width were found to significantly affect the dragline productivity larger size trucks were preferable to smaller size trucks in the pit configuration along an apparent dip. The cost analysis results showed that the pit configuration along the seam dip was more economical than the pit along the strike or along an apparent dip.

Jan 1, 1984

By J. D. Miller

Contact time during bubble/particle collision is calculated by taking into considera¬tion the effect of bubble and particle motion, buoyant force, bubble size, and particle size and specific gravity density for different cases of collision. From this motion analysis approach for the prediction of contact times and from bubble attachment-time measurements,, fundamental aspects of flotation such as flotability, kinetics, and separation can be explained and are discussed with respect to the effects of bubble/particle motion, bubble size, particle size, and attachment time.

Jan 1, 1987

By James H. Boettcher

In the second quarter of 1979, ASL Inc. inquired whether Crocker National Bank ("CNB") would provide $4 million in term loan financing to help ASL acquire the outstanding shares of the S&S Coal Company in West Virginia. ASL had, prior to approaching CNB, sought financing with the assistance of a financial advisor from a number of commercial banks without success. A summary of the initial terms requested by ASL is shown in Table I compared with the actual terms the transaction closed with. It is not difficult to note that the two sets of terms differ significantly. This is often the case when financing requests based on the expectations and vision of a mine developer are juxtaposed with more pragmatic requirements of a commercial bank. The "art" and fun of structuring financing plans for mining ventures (highly leveraged acquisitions or grass roots) comes in working with mine developers to arrive at a final financial structure that meets their objectives and constraints as well as those of the bank or other financial institution providing much of the financing. This article briefly describes the process we went through with ASL beginning with the terms they requested initially and ending with the ones on which the transaction was finally closed.

Jan 1, 1981