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By Milton E. Wadsworth

INTRODUCTION The purposes of this conference are aimed mainly at the treatment of fine or ultra fine particles in terms of beneficiation and chemical processing of minerals. For this reason the discussion on leaching will be confined to processes which treat slurries rather than those which treat a large variety of low and medium grade materials by vat leaching or dump leaching techniques. This eliminates such hydro-metallurgical systems as solution mining from consideration. This discussion will focus predominantly upon the behavior of fine particles as associated with their chemistry in leach reactors. Four major sub-headings may be pointed to as encompassing the major areas in which research and engineering design activity should be directed. These are: 1) generation of fine particles, 2) heterogeneous kinetics of leaching, 3) solution chemistry, 4) engineering design and control of flow reactors. Each of these topics will be addressed briefly in this presentation to illustrate current developments and future needs. GENERATION OF FINE PARTICLES As will be pointed out more quantitatively in the next section the generation of fine particles has great influence upon leaching systems inasmuch as in most cases the rate of leaching is related to the surface area of the particles involved. This is true for acid or base leaching of oxide minerals as well as a large variety of sulfides which have been considered in commercial processes and which have in the case of copper received increased attention during the past decade. Mean particle sizes of slurries vary broadly depending upon the type of grinding equipment being used. For example, in the agitation leaching of uranium ore the slurry typically consists of particles approx-

Jan 1, 1979

By Daryl R. Tweeton, William H. Engelmann, Orin M. Peterson, Jon K. Ahlness, Gregory R. Anderson

The Bureau of Mines measured the geochemical changes as H2SO4 was used for in situ uranium leaching by Rocky Mountain Energy Company near Casper, Wyoming. Cores and ground water were analyzed before leaching. Water samples were taken from observation wells located between injection and production wells as the leach solution was brought up to full strength in several steps. Measurements were made of pH, Eh, temperature, conductivity, total dissolved solids, dissolved oxygen,HC03, U. V, Na, K, Ca, Mg,S04, CI, Mo, Mn, Fe, AI, Si, F, P, As, and Se. The data were gathered to assist in geochemical modeling of leaching and to study the potential environmental effects of acid leaching. Environmental considerations appear favorable. For example, the concentration of Se, a toxic element often found in uranium deposits, stayed below the EPA standard for drinking water.

Jan 1, 1979

By J. Randel Hill

The 64th Texas Legislature passed the "Texas Surface Mining and Reclamation Act," Chapter 131, Texas Natural Resources Code (subsequently referred to as "the Act"), at a point in time when little surface mining had taken place within the state. Thus, enactment of regulatory control governing mining operations in our state has, for the most part, preceded widespread, intensive mining activity. I should point out that the statute applies only to the extraction of coal, lignite, uranium and uranium ore. A recent opinion rendered by the Attorney General's office has stated that extraction of the named elements, when it occurs incidental to the extraction of other materials, e.g., clay, is not not an activity subject to the Act. An important theme of the Act, frequently overlooked in other environmentally oriented legislation, is recognition of the Act's affect on the mining industry. The Act states that "the extraction of minerals by surface mining operations is a basic and essential activity making an important contribution to the economic well-being of the state and nation" and, in reference to reclamation being accomplished contemporaneously with mining, provides a recognition that "the extraction of minerals by responsible mining operations is an essential and beneficial economic activity." This legislative recognition is, of course balanced against the need for proper mined land reclamation, the rights of surface owners, the need to guard against unreasonable degradation to land and water resources and numerous other actions or events that the Legislature wanted protected. Another rather pervasive general theme that is established in the Act is the concept that the agency is entitled to obtain whatever information, or take whatever action, that appears reasonably necessary to effectuate the purposes of the Act. This concept, coupled with the detailed requirements placed on mining operations in the portions of the Act dealing with Permit Applications, Reclamation Plan and Reclamation Standards, easily insures that surface mining activities can and will be regulated to the extent necessary. Section 131.102(b)(2) is probably the most relevant provision in the Act which deals with the preclusion of mined lands becoming waste lands. This portion of the Act states that the surface mining operator shall: ". . . restore the land affected to the same or a substantially beneficial condition. ." In this language the Legislature had made it abundantly clear that the abandoned or orphaned lands found in some of the Eastern states, will not be tolerated in this State, and provided the Commission with a degree of latitude to determine what condition would be appropriate in each individual mining situation. I bring this area of the Act to your attention because it is the area which has received the most inquiries and concern by operators, i.e. what does "substantially beneficial" constitute? The Commission's staff has spent a considerable amount of time wrestling with the statutory language "substantially beneficial" to determine the legislative intent and provide operators with guidance of what they can expect. In this regard, the most definitive criteria in our opinion lies in the Act's legislative hsitory. The Legislature had before it basically three reclamation standards namely: House Bill 656, considered to provide the most stringent reclamation standard and identical to Senate Bill 66; House Bill 1717 which was supported by industry spokesmen and was considered to contain the least stringent reclamation standard; and Senate Bill 55 which was adopted by the Legislature. During the Bill's initial hearing before the House Environmental Affairs Committee, the House sponsor of the Senate Bill 55, which was the Bill eventually adopted, made the following statement: (I am quoting verbatim from the Committee's transcript although substituting the speaker's reference to the authors names with the Bill's numbers.) "An example of the differing approaches of the four bills can be seen in the area of reclamation standards and this is critical. House Bill 656, talking about restoring the surface of the land, House Bill 656 has this statement: 'At least fully capable of supporting the use to which it was capable of supporting prior to any mining or any higher or better use.' In other words you have to restore it to the level it was prior to the mining. Senate Bill 55: 'Restore the land to the same or substantially beneficial use.' Substantially beneficial use. (Emphasis his) House Bill 1717 says: 'Restore insofar as practical to appropriate beneficial post-mining use.' So that House Bill 1717 said to, 'restore insofar as practical to appropriate beneficial use. I think that's too weak, whereas I think the House Bill 656 that would call you to restore it to at least the use it had prior to the mining may also be too tight the other way. I think the Senate Bill 55 approach is down the middle of the road which says that you do restore it to the 'same or substantially beneficial use,' is a proper way to go there." Therefore, the conclusion that we have drawn from the legislative history of the bill is that the extent of reclamation required by "substantially beneficial" may be something other than the use it was prior to

Jan 1, 1979

By David J. Raden

INTRODUCTION Economic deposits of phosphate are found at shallow depths (80 ft.) in central and northern Florida (Figure 1) where they have been mined since the late19th century(l).The present (1978) mining rate is approximately 40 million short tons per year of product (called “phosphate rock1”), which represents approximately 80% of the total U.S. production and 30% of the world production. The principal use of Florida phosphate is for the manufacture of fertilizer. There are 10 major mining companies and 20 active mines in Florida at the present time, strip mining approximately 5000 acres per year. The ore, known as "matrix," consists of gravelly clayey sands containing phosphate minerals (principally carbonate fluorapatite), quartz, and clay minerals. The clay to phosphate ratio is generally about 1:1 by weight and the sand to phosphate ratio ranges from, 1:1 to about 3:1. Mining is done by large electric draglines, which strip and cast the sandy overburden soils, generally 10 to 40 feet deep, and remove the matrix, generally 10 to 25 feet deep. Dragline bucket capacities are generally 20 to 45 cubic yards, but range up to 65 cubic yards. Mining cuts are usually 300 to 500 feet wide and up to several thousand feet long. The ore is cast into an earthen sump where high pressure water guns are used to slurrify it. Centrifugal pumps move the slurry through a pipeline to a beneficiation plant where the phosphate rock is separated from the waste sand and clays.

Jan 1, 1979

By Stanley D. Michaelson

Stanley D. Michaelson retired in 1976 as chief engineer, Metal Mining Div. and director of the Engineering Center for Kennecott Copper Corp. An active consultant on mining and metallurgical assignments, Mr. Michaelson is also currently adjunct professor of mining engineering at the University of Utah. He received his B.S. degree in mining engineering from Lehigh University in 1934 and an honorary E.M. degree from the Montana School of Mines in 1961. Mr. Michaelson received AIME's Robert H. Richards Award in 1962 and was named a Distinguished Member of the Society of Mining Engineers of AIME in 1975. He has served as a Director and as a Vice-President on the AIME Board of Directors and is a Past President of the Society of Mining Engineers. He became an Honorary Member of AIME in 1978.

Jan 1, 1979

By A. J. Erickson, W. J. Garmoe

In mid-1970, Park City Ventures, a Utah partnership of Asarco and the Anaconda Company, initiated a six-phase exploration and development program in the Park City District, Utah. Geologic studies had delineated a number of exploration targets in several areas of the district. Discovery of ore in any of the target areas and continued favorable downdip development below then productive ore bodies would allow for reserve expansion and mill construction. The targets were: replacement mineralization in the Mississippian Humbug formation below productive ore bodies on the east flank of the Park City anticline; replacement mineralization in the Humbug formation in an unexplored fault block in the footwall of the Hawkeye structure on the east flank of the anticline; vein and replacement mineralization along the Silver Fissure; potentially higher grade replacement mineralization in the Humbug formation in a theorized structural block on the west flank of the anticline beneath the Ontario vein; replacement mineralization in the Permian Park City formation in the West End shaft area of the Silver King mine; vein mineralization along the Back vein in the Judge mine. In 1971 the Judge and Silver King Projects were suspended, due to a 30% cutback in the exploration budget. In spite of the cutback additional reserves were developed below the Humbug East Flank ore bodies; a major zone of ore grade mineralization was discovered along the Silver Fissure, five new ore bodies were found in the Humbug and Doughnut formations on the west flank of the anticline beneath the Ontario vein. First concentrates were shipped from a new mill in May 1975.

Jan 1, 1979

Problems discussed and research opportunities identified during the workshop in the major areas of 1) flocculation, 2) flotation, 3) leaching and magnetic separation are summarized below. I. FLOCCULATION Problems Practical problems caused by unintentional flocculation or dispersion were described in the papers that dealt with iron ore processing, selective flocculation, fine coal processing, phosphate processing and potash processing. Ideas generated during the discussions ranged from the very practical suggestion that a conscious effort be made to transfer knowhow from the experienced clay industry to the metals and fuels-from-slimes industry. . . , to the familiar appeals for omnipotent theoretical developments. There was surprising recurrence of some questions in many contexts. Recurring questions are emphasized here rather than commodity-specific problems because their answers would serve a wider clientele usage. There is indeed no objection and some advantage to commodity-specific research, however, provided the proposed project is planned with full cognizance of transferable knowledge in other commodities, and of the possible usefulness of these results in other areas. Research Needs Most of the questions or research opportunities can be classified into three groups: a) water chemistry, b) dewatering, and c) flocculation theory. Other classifications are possible and probably useful. In each group there is a clear need for outwardly esoteric theoretical research a clear application of that work to current practical problems. Higher priority should be given to proposals for theoretical research which explicitly show the expected ultimate usefulness of the result. Likewise, proposals for applied research should demonstrate cognizance of applicable theory. Both of these types of projects could profit from collaboration among industrial, university and government personnel.

Jan 1, 1979

By R. Stratton-Crawley

Flotation-related processes utilizing an oil phase for processing fine mineral particles have been described and various applications discussed. The problems associated with the techniques are varied, but may be summarized by the following areas; (1) applicability to fine particle beneficiation, e.g. collector extender and emulsion flotation. (2) major 'mechanical' problems, e.g. emulsion breakage and oil recovery in oil flotation. (3) complex interfacial chemistry, e.g. empirical nature of pigment flushing .

Jan 1, 1979

INTRODUCTION The first installation of large, commercial, high gradient-high field cannister and matrix magnetic separators for removal of impurities from kaolin was made in 1973 (1). Since then the technology and equipment have been widely adopted for clay processing with about 12 units in commercial use. These new separators have filled a need, caught the imagination of many and become a technology worth fighting for. A fight has occurred, and a resolution on royalties for kaolin processing, at least, has been achieved. LIMITATIONS TO APPLICATIONS OF MAGNETIC SEPARATORS Other than the use of these magnets on kaolin clay, no other application has yet achieved widespread adoption. Dr. Iannicelli blames inertia, and1 would agree that it is a factor. There are other reasons too, and if they are examined, they may isolate problems that R&D can significantly assist in solving. I'd like to break the problems into two areas. Machine limitations - the mineral properties are there but performance is insufficient or uneconomic. Separation limitations - the mineral properties aren’t there, but the magnetic separation would perform well if the properties were there (size is right; concentration is right, etc).

Jan 1, 1979

By Garland R. Dever, Preston McGrain, George W. Ellsworth

Limestone resources for industrial, constructional, and agricultural uses occur on the surface and at minable depths in several areas along the Ohio River and its navigable tributaries in Kentucky. High calcium and high carbonate limestones suitable for use in cement and lime production, steel manufacture, environmental control measures, and other special uses are present in the High Bridge Group (Ordovician) and Warsaw and Ste. Genevieve Limestones (Mississippian). Deposits with thicknesses of 7.3 to 20.7 m,(24 to 68 feet) have been documented by the analysis of samples taken at 0.3-m (1ft) intervals. Active and potential mine and quarry sites afford access to water transporation and proximity to a number of industrial and metropolitan centers. Geologic factors affecting the distribution of deposits include the Cincinnati arch, regional dip into the Appalachian and Eastern Interior basins, complex faulting in and near the western Kentucky fluorspar mining district, and late Paleozoic erosional unconformities in northeastern Kentucky.

Jan 1, 1979

By Frederick W. DeVries

Since we first agreed to present this talk we have learned that some of you may have been covering ground we intend to discuss: Bob Schechter, Daryl Tweeton, Don Seidel, Herb Burgman; however, the ideas were original when we began, "novel" as in the title of the talk, and whether our results are news or merely corroborative, we feel they point a direction that could be valuable to all. We worked with many of you in the past on using hydrogen peroxide in in-situ uranium leaching. Our talk today is not directly related to peroxide; it is, I hope, illustrative of Du Pont&apos;s interest in providing service to this industry in any way we can. The scouting work we are presenting was stimulated by field inputs: First, ammonium carbonate leaches cause restoration problems, primarily because ammonium ions exchange on clays with calcium. Second, sodium carbonate solutions, especially in South Texas deposits, can cause intolerable swelling of clays. From discussions with Dr. van Olphen, who wrote the book on clay chemistry, we inferred by comparison of the radii of the hydrated ions of the elements in these clay systems, that since potassium had about the same radius as ammonium, and sodium was much larger, potassium occupied a unique position to solve both problems. We have shown: FIGURE 1 Potassium bicarbonate systems leach uranium without loss of permeability found with sodium Potassium salts are very effective in restoring ammonia-leached sites Before reviewing the details of our work, which was performed by Hazen Research, Inc., I should like to stress its scouting nature. We are trying to assist the in-situ industry by pointing out new, potentially important directions. But, as with our previous work on sodium silicate to restore permeability, we feel the development phases can generally best be carried out in cooperative programs with companies directly involved with operations. DISCUSSION Test Parameters Now for the details: Our leaching tests were designed to note pressure-drop changes across the ore sample as the uranium was leached. Figure 2 shows the apparatus. The [ ] packed length was 20.5 inches (52 cm) with fifteen hundred grams of ore in the two-inch (5 cm)-diameter bed. Pressure drop was measured by manometer and feed rates were maintained constant with a tubing pump. The samples, from a South Texas leach site, were sealed in "Zip Loc" bags, frozen with "dry ice", crushed (still frozen) through six mesh, and blended before placement into the columns. The ores analyzed as shown here: FIGURE 3 Ore Analyses [Sample A Sample B U308 015% 0122% Mo 0004% 0086% Se0012% <0001% Fe3,078%076% Fee- 098% 044%]

Jan 1, 1979

By A. F. Banks

INTRODUCTION Selective flocculation-flotation as a method of desliming potash flotation feed has been practiced in the Cominco Ltd. potash plant since November. 1974 when it was installed to replace a less efficient mechanical desliming process. The plant was designed for a consistent feed containing 4.5% insolubles. In practice the quantity and quality of the insoluble material is quite variable. This variability led to serious problems in the deslime circuit and consequently had an adverse effect on sylvite flotation performance. A costly mechanical solution to the problem was being seriously considered when it was drawn to our attention that a selective flocculation-flotation process had been developed. The process was tried first in the laboratory on the Cominco Ltd. ore, then on a pilot basis on 25% of the mill feed and finally full scale. The time from being informed of the process to full scale operation was 18 months. It has since been incorporated into a tailings regrind circuit. The original mine design called for the mining of an 11 foot height up to the top of the three clay seams. These had to be taken as they were a zone of structural weakness. It also assumed that the beds would be uniform with only a few disturbances. Very soon after the initial start up it was found that permanent openings had to take in the layers right up to the upper clay seams and because of the mining process that this material would have to be milled when encountered. The number of disturbed areas in the mine is greater than the design anticipated. In operation the insoluble content of the mill feed varies from 4.5% to 8% plus with the peaks being very short- term to relatively long, from hours to day. In terms of quality, the insolubles in the mining horizon are relatively soft and easily liberated, whereas those above are hard and liberate slowly.

Jan 1, 1979

In their presentations Dr. Puddington and Dr. Stratton-Crawley have concentrated on spherical agglomeration and two-liquid extraction respectively. I should like here to complete the picture by putting these two techniques together in context with other techniques in which non-polar oils are used in the concentration and separation of minerals. Although these techniques are invariably treated separately and have been studied in isolation, there is a lot to be said for considering them together and trying to systematize their similarities and differences. This I take as a principle guideline in my introduction to this discussion. Four processes can be distinguished on the basis of the dosage of oil required: --simple flotation with collector-extender --agglomeration (emulsion) flotation --spherical agglomeration --two-liquid separation Dr. Stratton-Crawley has suggested that "pigment flushing" could find application in the treatment of ores. This is an interesting suggestion. However, the process can be regarded as a variant of two-liquid extraction, and it is convenient for me to do so in this discussion. Table 1 sets out some main features of these techniques. The first, in which the oil is used to enhance the strength and reduce the dosage of the collector is not designed for and has no special advantages in the treatment of fines, and therefore will not be further treated here. To add to the details appearing in the Table, thumbnail sketches of the other three, which all do show particular efficacy in the treatment of fine particles, are given below.

Jan 1, 1979

By John J. Childress, Russell L. Cook

Stringent environmental regulations, which have limited the use of sludge ponds, coupled with the economic incentive to clean more coal or to add fine coal cleaning additions to existing preparation plants have increased the use of static thickeners in preparation plants. The Lamella Gravity Settler, sometimes designated Lamella Thickener, is a shallow depth sedimentation device which has been applied in a variety of industrial process and wastewater control projects in place of the conventional raked thickeners. This paper presents the theory and design of the Lamella Thickener, as well as describing the operating results from several full scale installations in a variety of Appalachian preparation plants.

Jan 1, 1979

By R. V. Ramani, R. M. Mishra, Y. J. Wang

The validity of the concept of mine resistance in ventilation systems is examined. Mine resistance is the proportionality constant relating the head generated by a fan and the quantity flowing through it when the fan is connected to a mine circuit. It is the total effect of all branches in the mine ventilation circuit. Its importance lies in the fact that for new mine projections, and in the extensions of existing mines, ventilation calculations are usually based upon adjustments of the mine resistance. In ventilation circuits with regulation, and/or with multi-fans, simple adjustments of the mine resistance curve do not lead to correct solution. A ventilation system consists of several interconnected subsystems where one subsystem behavior affects that of the others, and the total system. Through a series of simple but realistic examples, the authors demonstrate the importance of the systems concept in mine ventilation, and its practical application to coal mine ventilation planning. Starting from an initial system with no leakage and one fan, more complex ventilation networks with several leakages, sections and fans, are analyzed to show that ventilation system design on the basis of total systems approach is the correct procedure.

Jan 1, 1979

By Raymond E. Zimmerman

The Swirl Cyclone developed in Japan, although based upon the same principles as the standard cyclones for heavy-media or water-only cyclones for cleaning coal, is novel in that it is invested with the apex on top, discharging rejects at the top, and clean coal at the bottom. It also uses a variable air vent tube for controlling the vortex. Tests conducted indicate that its efficiency is not only as sharp as standard cyclones but it also performs using a much coarser grain magnetite, promising higher magnetite recovery. The author describes the results of tests conducted in Japan on a very difficult coal.

Jan 1, 1979

By J. P. Matoney, E. J. Sandy, D. A. Dahlstorm

INTRODUCTION Before an understandable discussion concerning coal dewatering processes can be initiated, it is necessary to define some terms of usage. The many different meanings and interpretations of terms preclude development of standard definitions so the terms defined in this chapter should be regarded primarily as working terms intended to facilitate communication.

Jan 1, 1979

By John Cogan

Field observations were made of rock phenomena in shale, dolomite, and fractured quartzite in the Burgin Mine, Eureka, Utah. Draft closure rates were measured with extensometers and convergence gages. In addition the effects of hydraulic props upon the retardation of closure was also monitored. Drift closure rates were found to be constant and to vary between 0.32 x 10-8 min-1 for dolomite and 23.8 x 10-8 min-1 for soft shale. The installation of props set at constant load served to retard the closure rates. General results show closure to occur at a constant rate for all cases, to be non-uniform around the drift openings, and to be increasingly retarded toward a zero rate by increases in prop load.

Jan 1, 1979

By Howard M. Wells

The investment worth of a mineral deposit can only be realistically evaluated in relation to specified engineering design criteria which fully detail the proposed method of exploitation. The operational design of a mine falls essentially within the technical discipline of the mining engineer, under the constraint that the technical design should be aimed at optimizing the financial attractiveness of the project. In the case of a marginally viable proposition it becomes vitally necessary to identify the best set of design parameters which together will add up to an optimum investment proposal. This paper examines some fundamental logic of optimization for a "wasting asset" type of investment such as a mine, with special reference to the rate of annual production and the strategy of selective mining.

Jan 1, 1979

MINING; SOLUTION U.S. 4,066,297 - In the solution mining of uranium from an underground deposit of uranium ore using an alkaline leaching solution, precipitation of alkali metal salts is avoided by maintaining the Injected leach solution of an alkaline carbonate or bicarbonate and an oxidant undersaturated with respect to carbonates Undersaturation is effected by use of a water softening unit or by bleeding a portion of the recycled alkallne leach solution. A P. Spence, assigned to Atlantic Richfield Co Jan. 3, 1978 4 pp. (299-4). Filed: 6-1-76 (69 1,344)

Jan 1, 1979