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By P. A. K. Wilkinson

This paper is concerned with the development of an in situ recovery of boric acid from a deep-seated colemanite deposit in California. The deposit contains 147 million tons of borate ore containing 6.4% boron oxide (B203). It is the largest undeveloped colemanite deposit in the United States and because of its unique occurrence and grade, in situ extraction appears to be the most economic viable process. The paper covers the geological, mineralogical, hydrological, well-field development, and extraction considerations leading to the initial pilot plant and subsequent demonstration plant phases of the project. Market potential aspects and preliminary economics of the project are also covered.

Jan 1, 1987

By Hans von Michaelis

The renaissance in extractive metallurgical practices for gold and silver recovery is far from over. This is one conclusion of a three year investigation into innovations in Cold & Silver Recovery by Randol International Ltd. (1981, 1983). The six volume reference report reviews a host of new processes and innovative applications of older metallurgical practices. Some of these were summarized by von Michaelis (1982, 1982a). There are several reasons to expect this renaissance to continue. One reason is the nature of gold and silver deposits. The list of known occurrences of These metals is very extensive. There are literally tens of thousands of prospects but over 99% of these are too low grade, too small or too refractory for a viable operation employing conventional processing.

Jan 1, 1983

By B. J. Scheiner

The Bureau of Mines has developed a system for dewatering waste slurries by flocculating mineral particles with polyethylene oxide (PEO) and dewatering the resulting flocs on static and/or rotary screens. This paper discusses data obtained from dewatering, rheology, and ion-exchange experiments. A possible mechanism is postulated for the attachment of PEO to claylike particles through a water bridge with the intershell waters of the exchanged ion and the polymer.

Jan 1, 1986

By T. C. Vogt

The past history of uranium production has been dominated by strip and shaft mining methods, but recently in-situ leaching has emerged as a viable alternative for uranium recovery. (1-8) Mobil was the first company to start in-situ uranium leaching in New Mexico. Mobil's Crownpoint project areas are in Mdinley County and are part of the Grants Mineral Belt. The major uranium deposits in this area occur in the Westwater Canyon Member of the Jurassic Morrison Formation. (9-11) The ore depth at the Crownpoint project is about 2000 ft. In an earlier paper we discussed the uranium mineralogy of an areally broad sampling of Crown- point ore. (12) The organic carbonaceous material often associated with the coffinite ore was characterized in some detail. The organic material appeared to be a very mature, coaly-type kerogen derived from plant components. This result was consistent with other studies on such carbonaceous material. (13-15)

Jan 1, 1981

By John P. Hunt

Early disseminated copper mineralization at Quebrada Blanca, Chile, accompanied 38 million year old quartz monzonite stocks and dikes. Early mineralization was followed by hydrothermal mineralization, mineralized breccias, and post-mineral faulting. After supergene leaching and enrichment, Quebrada Blanca was buried under late Tertiary gravels, and then partially re- exposed in Quaternary time. Based on work to date the orebody appears to contain more than one hundred million tons of plus one percent secondarily enriched copper ore, overlying several hundred million tons of protore averaging more than 0.5% copper. A source of industrial water appears to have been located. Pilot scale metallurgical tests, mine planning, and feasibility studies are in progress.

Jan 1, 1981

By William R. Nash

Case histories of water problems in underground mine shafts and tunnels are outlined to illustrate varying degrees of sophistication in grouting techniques currently applied in such construction. The interception of water underground can be one of prior knowledge, i. e., the site investigation provides necessary data to plan a grouting program prior to construction start, or excavations may encounter "changed conditions" or unplanned water. The latter includes catastrophic inflows and emergency situations where the structural integrity of a building or concrete shaft lining are jeopardized. The presentation of this paper outlines some applications of grouting work in underground mine construction throughout the United States in a variety of geological provinces and for a variety of minerals.

Jan 1, 1984

By Mary E. Learmont

Grinding with steel media adversely affects the flotation response of galena. Electrochemical measurements, flotation tests, and AES, XPS, and STEM examinations were employed to identify interactions between galena and mild steel. Iron oxide, hydroxide, or sulfate species that formed on the galena surface upon contact with mild steel decreased its floatability, with the time of contact and aeration condition affecting the severity of the flotation depression.. Parallel tests performed with an active metal, magnesium, indicated that floatability was also affected by the presence of a surface coating involving lead species.

Jan 1, 1984

By E. M. Schern

The Morenci/Metcalf porphyry copper mining operation, located in southeastern Arizona, currently processes approximately 100,000 tons of ore per day and has copper ore reserves estimated to be in excess of one billion tons. Functional groups within the Geology Depart¬ment (currently staffed with six professional and two support personnel) include mine geology, project geology, and hydrogeology. The primary task of mine geologists is daily preblast bench face mapping with grade and mill amenability estimates. Auxiliary duties include detailed in-pit metal distribution evaluation, mineragraphic work and flux quarry geology. Project geologists conduct explora¬tion and preliminary development projects both within and outside the Morenci district and provide support to ore reserve block modeling and geotechnical work performed by the Morenci mine engineering group. Hydrogeologists handle exploration for and development of groundwater' resources and groundwater flow modeling, mine dump leach solution penetration and recovery evaluation, and tailing dam water reclamation.

Jan 1, 1983

By James E. Lawver

During the past century, the Florida Phosphate Industry has established an enviable record of innovative technology in nearly all aspects of mining and beneficiation. A notable exception is the lack of technology to improve the present practice of storing waste clay in earthen dams. The rule which has been adopted by the Department of Natural Resources states, "Since storage of clay wastes for long periods of time interferes with expeditious reclamation and since above grade storage of clays takes otherwise useful land out of production and raises potential health and safety problems, below grade storage and rapid reclamation techniques are encouraged." The two waste products from the beneficiation plant are clay slimes (-0.1 mm in size) and sand tailings. The sand tailings do not present a problem since the tailings rapidly dewater to a dry weight of about 100 pounds/ft3 and make good land fill. By contrast, disposal of waste clay slimes is a formidable task. The basic problem is simply that the waste clay not only dewaters very slowly, but also that the ultimate solids content is very low and in most cases the volume of the clay greatly exceeds the available volume of below ground storage of the mined land.

Jan 1, 1984

By W. H. Stahl

The continuous vacuum filtration is the solid-liquid separation process that is nowadays most frequently used in the beneficiation industry all over the world. After a development time of several decades, the various filter types such as drum filter, disk filter, plate filter and belt filter can be consideres as a sound functional design ensuring a trouble-free operation. Nevertheless, the vacuum filtration does no longer meet the present and future technological requirements. The moisture content of filter cakes is too high. Their thermal secondary drying is too expensive (coal, ores) and may bring about undesirable material changes and the filter cake conditioning with water-binding substances for dumping purposes is too costly.

Jan 1, 1983

By Franklin H. Sharp

During the last few years the New Lead Belt of South- eastern Missouri has become the main source of lead in the United States. It also produces significant amounts of zinc, copper, and silver. The mines are located on a narrow, mineralized trend extending southward from Viburnum, Missouri for about thirty-five miles. The area is part of the Ozark uplift and consists of steep-sided, heavily wooded hills with narrow valleys. Surface streams are very erratic, normally having low flows but becoming rushing torrents during the violent thunderstorms that occasionally occur. Because of the pristine nature of the country and the newness of the mining developments, the environmental impact of all phases has been closely watched.

Jan 1, 1973

By Robert W. Row

The run-of-mine coals in the U.S. being fed to coal cleaning plants have become increasingly finer due to the adoption of modern, mechanized mining methods, and economics are dictating that finer fractions, as well as the coarser fractions, be cleaned. Traditional dewatering methods (vacuum disc filters and centrifuges) are proving inadequate for preparing fine refuse for disposal or fine coal product for downstream handling. The Electric Power Research Institute has been supporting research into the nature and limitations of mechanical dewatering, and novel ways of improving it. The efficiency of various silicone-based chemicals at aiding dewatering was investigated, and it was shown that the final moisture content of hydrophilic coals after vacuum Filtration could be reduced by 1 to 5% with up to 40% increase in filtration rate by addition of one of several of these silicones. EPRI also has an on-going program at its Coal Cleaning Test Facility to investigate the performance of the Larox pressure filter in comparison with that of the disc filter and solid bowl centrifuge. While improvements to the dewatering performance currently being obtained in existing operating plants by such means are achieveable, a fundamental study has shown that, regardless of changes in operating conditions, there may be a limit to the lowest cake moisture content attainable by mechanical dewatering of a given sample of coal fines. Determination of this limit for a specific coal would be useful in designing facilities to dry and handle it.

Jan 1, 1984

By D. G. Chedgy

Careful consideration is given to the type of cleaning equipment and control sys- teas to be used when selecting circuits for wash-ing fine coal (28M x 0 size fraction). However, the desliming, declaying and sizing procedures required to ensure efficient operation normally are not evaluated in sufficient detail resulting in disappointing system performance. This paper details desliming and dewatering circuit design which is extremely effective based on recent test data. The circuit maintains control of the 28M x 0 (declayed) size fraction with minimal misplaced material and maximized circuit efficiency. A discussion of circuit design parameters and control systems, as well as results from the testing program, are included in this text.

Jan 1, 1986

By G. A. Irdi

An automated method of microscopy for determining the pyrite size distribution on two base coals that were crushed to 28 mesh x 0 has been developed. Polished epoxy-bound coal pellets were prepared and examined by a Zeiss IBAS image analyzer utilizing a program developed from provided software. Pyrite size distribution determination is considered a necessary first step in pyrite characterization that could lead to successful predictions, by microscopy, of a coal's theoretical pyritic sulfur removal. Our research efforts to date have indicated that the IBP-S can be a reliable instrument for determining pyrite size distribution in crushed coal. A program was also developed to convert pyrite size data to a weight basis for comparisons to the results from chemical analyses. The problems encountered in our research and their solutions will be presented in the discussion.

Jan 1, 1986

By David L. Martin

This paper discusses the development of a SLAM II* simulation model with imbedded optimization modules designed M evaluate mineral exploration and exploitation strategies. The model traces through a sequential exploration program, evaluating each deposit site based upon geologic information and potential profitability of the site. At a specified time during the simulation, a new production plan is developed for currently producing deposits which takes into account the planning horizon and deposits which are currently being explored. Potential uses of the model by geologists, engineers, and management decision makers include setting corporate objectives and policies on exploration and production. The model is also useful for testing past decisions to evaluate decision making criteria and evaluating mineral deposit profit potential.

Jan 1, 1983

By H. Colin

The basic industry, such as mining, ferrous and non-ferrous, cement and aggregates, stores and handles millions of tons of raw materials, re- quiring often different types of storage, blending and reclaiming systems.

Jan 1, 1980

By R. E. Ray

As coal reserves at shallow depths continue to be exhausted, a number of U.S. coal mining companies are beginning to develop coal seams previously thought to be coo deep to mine economically. Because of increased cover load, mines operating in deeper seams face unique ground control problems. In addition, the volume of methane gas contained in coal beds increases with depth, and ventilation requirements are much more stringent for deep underground coal mines than for shallower mines. When the longwall mining method is used at great depths, ventilation, ground control, and operational considerations must all be addressed in the design of longwall panels. This paper examines the influence of these factors, particularly ventilation and operational considerations, upon the feasibility of two, three, and four-entry longwall development panels in Jim Walter Resources' four deep mines.

Jan 1, 1986

By Choon K. Quan

Subsidence is a surface manifestation of the underground development and exploitation of minerals, and its impact on the environment is becoming of increased concern, particularly in the face of an accelerating demand for energy and minerals. In the United States, the state-of-the-art in subsidence prediction, control, and prevention and in subsidence-related damage abatement has not progressed to the level achieved in other countries. To bridge this gap, the Bureau of Mines, through its Mining Environmental Research program, is pursuing a comprehensive subsidence investigation, specifically designed to address major problems on the local, regional, and national level.

Jan 1, 1979

By W. R. Boehme

The test work was done in two parts. In Part I, five 6 x 16 mesh activated coconut shell carbon samples made by four different manufacturers were evaluated as to their gold loading rate and total gold loading. The five carbon samples tested are not identified by manufacturer and are simply designated as Types A through E. Then from the carbons tested, a suitable highly active carbon was selected for subsequent studies on impurity effects upon loading, Part II. Test Procedures The procedures and tests descriptions are given for the ultimate gold carbon loading tests and the dynamic gold carbon loading tests.

Jan 1, 1983

By Joseph M. Zigich

The Anaconda Minerals Company operates a molybdenite and copper producing mine and mill facility near Tonopah, Nevada. Included with the milling facility is a ferric chloride leach plant for removal of copper mineralization from the molybdenite concentrates. Discussed are the engineering and construction schedules associated with the leach plant. The chemistry associated with the process along with a description of the process flow, equipment, and operating parameters are contained in the paper.

Jan 1, 1983