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By Thomas J. Wright

The evaluation and development of the Eastern North Carolina phosphate deposit resulted in one of the world's largest and most modern phosphate mines and fertilizer complexes at an investment in excess of $90,000,000. The resulting ore beneficiation process showed excellent correlation with pilot plant data. A number of variations from current industrial practices were introduced and projected from bench scale tests through pilot plant to production. Principal among these variations were the following: 1) removal of magnesium by classification, 2) simultaneous flotation of coarse and fine phosphate, 3) the use of saponified fatty acid, 4) utilization of filter wash water for deoiling, 5) utilization of a rougher concentrate for acidulation, 6) calcination of flotation concentrates, and 7) elimination of grinding prior to the manufacture of phosphoric acid.

Jan 1, 1971

By Philip R. Whitney

Precipitation of hydrous manganese/iron oxides in streams can be readily observed in much of the northeastern United States, and is apparently a common phenomenon in other glaciated areas (1,2,3,4). Deposition occurs when Mn-enriched ground or surface water enters the stream environment and encounters conditions of higher Eh and pH. The preferred location for deposition is in shallow, fast-flowing segments of stream; the oxides usually form as coatings on detrital material. The experimental studies of Hem(5) and a considerable amount of work on marine and lacustrine manganese nodules(6,7,8) suggest that given an appropriate substrate, deposition of manganese oxides may occur even when the water is undersaturated in Mn with respect to the oxides, due to catalysis by organisms or by silicate, carbonate, or ferric hydroxide surfaces. Once begun, manganese oxide deposition is autocatalytic (9). Studies of the distribution of oxides in various size fractions of stream sediments indicate that the thickness and prevalence of the coatings commonly increases with increasing particle size in the coarse sand and gravel size ranges. Figures 1 and 2 show a fairly typical distribution of leachable metals over nine size fractions from 62 microns up to 8-16 mm. The leaching solution used was neutral ammonium citrate with hydroxylamine hydrochloride, which effectively removes the oxide coatings without significantly attacking most silicates, carbonates or sulfides. Figure 1 shows metal content as ppm of the total sample; figure 2 shows' the same data as micrograms of metal per square millimeter of surface area.

Jan 1, 1975

By Peter McKenna

Different reefs being extracted from a mine will, in all likelihood, have significantly different semi-variogram models - and these will probably vary from geozone to geozone. As errors of estimation are dependent on the semi- variogram parameters, it follows, if a mine samples all reefs in all sections using the same sampling grid pattern, that estimation errors (or limits of confidence) will not be the same throughout the mine. This may be an undesirable situation! A geostatistical study of the relative merits of alternative sampling arrangements has been carried out by considering different reefs in different sections of a South African gold mine.

Jan 1, 1989

By J. M. Mutmansky

This paper outlines the results of a study of opinions of practicing engineers concerning the value of environmental engineering courses in a mining engineering curriculum. One hundred engineers with significant experience in mining-related engineering work were carefully chosen. Of the sixty-seven responses received, about half were from mining engineers and half from environmental engineers. The results of the survey are outlined in detail. The number and type of courses recommended by the respondents are summarized as well as the specific topics recommended for inclusion in a mining engineering curriculum. The survey form also asked for the stages in the mine life when environmental experts were needed and the percentage of environmental engineering performed by outside experts for many mining-related environmental tasks. The results of this line of questions are provided. Finally, the paper offers a comparison of the results for environmental engineers and mining engineers and analyzes the differences.

Jan 1, 2001

By E. J. Karges

[For reasons well known to Mining Engineers, fine grinding in the wet form is quite universal inn plants engaged in the traction of metallic values from crude ore In the processing, of non-metallic and industrial minerals, however, fine grinding in dry form is the more common method. The crude materials generally contain less moisture than required for wet grinding, and the products are usually marketed or used in the dry form, most of them as powders. To grind wet would therefore entail the addition of water and the expense for drying the product, which is not justified. This paper will concentrate on the particle size reduction or fine grinding of materials to produce a dry powder]

Jan 1, 1963

By Joe M. Short

More than eighty years ago, in what we generally consider a more leisurely age, workers and engineers began the construction of the longest railroad tunnel in the world. When completed, the Simplon Tunnel ran more than twelve miles through the alps to connect Switzerland and Italy. Work began in 1898 and the tunnel was completed in 1905. In all it took about seven years to build one of the world's great tunnels. More than seven years ago, in what was hoped to be a rapid and constructive to the deaths of 38 workers in two spectacular tunnel disasters in 1971, the secretary of Labor's Construction Advisory Committee on Safety and Health began in January 1972 a search for an effective standard on tunnel safety. Much hard and useful work has been done, especially by the construction advisory committee' but more than seven years later, we still don't have a tunnel standard. We may speculate that, when the Simplon Tunnel was completed, workers and their bosses assembled to celebrate their achievement and to count their casualities. We have no need to speculate on the lack of achievement up to this time. An so far as I know, the bureaucrats have suffered no casualities except perhaps some unreported cases of ring-around-the-color. The only moral I can draw from all this is thai it is easier to penetrate solid rock than it is to get through bureaucratic fog. We can only hope that OSHA will finally take advantage of the work which was finished years ago and complete the actions necessary to give us a tunnel standard. Having made my point, I could stop my remarks right now; but

Jan 1, 1979

By W. D. Macleod

This paper describes a mineral dressing process for the upgrading of tin ores. The process described is called 'agglomeration' and. is similar in many respects to flotation. Many variables have been examined experimentally both on batch and continuous operations and are reported upon herein... Using a Mt. Pleasant tin ore, assaying 0.5% Sn, an upgrading to 8% Sn, with a recovery of 95% could be obtained by this process.

Jan 1, 1966

By K. Dagdelen

The definition and shortcomings of traditional cutoff grades are discussed. The concept of optimum cutoff grade policy which maximizes the Net Present Value (NPV) of annual cash flows coming from a mining project is introduced within the basic framework outlined by K. F. Lane. Several examples are used to demonstrate the shortfalls of cutoff grade policies obtained by various heuristic optimization techniques. An algorithm to obtain an optimum cutoff grade policy which maximizes the NPV of a project is given and described in detail.

Jan 1, 1993

By Robin J. Hickson

El Abra has mining concessions granting the right to exploit minerals in more than 130 km2 (32,122 acres). SCM El Abra owns “rights to occupy” the surface of these claims. The company also owns the surface rights over the process plant area and over land conveyor route. The project has procured all material easements relating to the mine area, processing facilities and access rights of way. Engineering, procurement and construction Figure 1 sets out the development and construction schedule for the project. Development is already well under way. As of early January 1996, about 70% of the project was complete and more than 80% of the capital expenditures were committed.

Jan 1, 1996

By John T. Bartlett

During the last decade, the increasing price of gold has renewed interest in the various metallurgical techniques for recovering precious metals. Much of the recent technology advance has been aimed at low grade deposits resulting in more complex processes and the necessity of tighter economic control. These factors along with more stringent environmental constraints have made it necessary to optimize each process to minimize energy and raw material consumption and reduce waste discharge. In most cases, detailed process analysis is required to detect inefficiencies and provide alternative solutions for process improvement. Also during this same period, the computer has become widely accepted and computerized mathematical modeling has been applied to an increasingly broader range of problems. Microcomputer based process modeling and simulation systems are routinely used to analyze and improve communition, hydrometallurgical, and pyrometallurgical processes for the recovery of precious metals.

Jan 1, 1987

By J. C. Norman

The United States was the world’s largest producer and consumer of boron compounds during 1995. According to estimates from the US Geological Survey(USGS), boron mineral concentrate and chemical production in the United States totaled an estimated 1.1 Mt(1.2 million st) yielding 602 kt (663,000 st) of B2O3 for an estimated value of $462 million. This level of production exceeded 1994 revised production figures by about 9%. The United States continued to provide nearly all its own boron supply while maintaining a strong position as a source of sodium borate products and boric acid to foreign markets. During 1995, about 900 people worked in domestic boron mines and plants, about the same as in1994. USGS estimated total world production of boron during 1995 to be about 3 Mt (3.3 million st), yielding about 1.6 Mt (1.8 million st) of B2O3. World production in 1995 was about equal to revised 1994 levels.

Jan 1, 1996

By Rameshwar Sah, Basavaraja Maribasappanavar, Sangamesh Desai, G. Balachandran, Ravi Kant Sagar

The present research work deals with the effective utilization of hematite ore containing goethite, kaolinite and gibbsite losson- ignition (LOI) phases in pellet making without deteriorating product pellet properties by optimizing the induration cycle especially drying and preheating of pellets. Adequate drying and preheating of pellets before sintering is of prime importance to sustain the desired properties of pellets. Green pellets of + 8 to − 16 mm size were prepared in a laboratory disc pelletizer and indurated by varying drying and preheating temperatures in a laboratory Raising Hearth Furnace (RHF). Produced pellets were assessed for physical and metallurgical properties. Improvement in drying and preheating temperature simultaneously helped in mitigating fired pellets’ property deterioration. Drying at 300 °C and preheating at 750 °C helped in the maximum removal of matrix LOI from the pellets before firing and enabled the production of pellets of desired properties. Laboratory scale findings successfully implemented at existing 4.2 MTPA capacity pellet plant of JSW Steel Ltd. Vijayanagar and high LOI iron ores (IOs) utilised which resulted in reduction of average monthly pellet fines generation by ~2 wt. %.

Jun 4, 2022

By T. Acton

The Zarafshan/Newmont Joint Venture is currently operating in the Republic of Uzbekistan producing in excess of 400,000 oz. of gold per year from low grade oxide ore stockpiles adjacent to the Muruntau open pit gold mine located in the Kyzylkum desert of central Uzbekistan. Four stage crushing and screening produces a final product for heap leaching, Merrill-Crowe processing, and local refining for International market export. The Zarafshan/Newmont Joint Venture is the first major commercial project of its kind in the former Soviet Union to be successfully negotiated, engineered & constructed, and placed into continuous operation,

Jan 1, 1997

By S. Todd Mickleborough

The geostatistical technique of conditional simulation is applied to measure the uncertainty in factor of safety predictions for soil slopes where there is incomplete knowledge of the spatial distribution of soil properties. A case study considers a natural clay slope in Canada. The sequential indicator simulation technique is used as a means for generating a series of spatial maps of soil properties for this site. These maps approximate random draws from the conditional probability density function that characterizes existing uncertainty in the spatial distribution. Factor of safety determinations are then made for each simulated map using the simplified-Janbu approach, where the computations are performed with a new computer program that can operate on irregular spatial profiles of soil properties specified on a discrete grid. A unique capability of this approach is the ability to generate the distribution of factor of safety conditional to the type, position, and value of existing site characterization measurements. This capability should reduce uncertainty in FS predictions.

Jan 1, 1993

By J. P. Wilson, T. Cook, H. Kling

The Tessenderlo-Kerley Leachprocess has been shown to be effective in the removal of residual copper from molybdenite concentrates. Concentrates of varying mineralogy, including those containing relatively large amounts of chalcopyrite, have been successfully leached on laboratory and pilot plant scales. The lixiviant system is ammonia andammonium bisulfite with air / oxygen addition. An abrasive is added which greatly enhances the kinetics, and it is subsequently screened out and reused. The dissolved copper is easily recovered using existing technology. Extraction profiles, reagent consumptions, and mineralogical data are presented.

Jan 1, 1999

By Joel L. Morrison

The preparation of coal-water slurry fuel (CWSF) has the potential to be a commercially viable technology for the coal industry. The technology base required to prepare stable CWSF using grinding circuits has been developed over the past decade and is now being applied to the preparation of CWSF from wet coal fines which are generated during coal beneficiation. When preparing CWSF, the optimum CWSF formulation must be determined to ensure that the fuel will be stable while having acceptable atomization and combustion properties, and the production run must be monitored closely to ensure that the CWSF quality is maintained. This paper describes the CWSF formulation process, CWSF preparation circuits, and some of typical problems encountered in, and solutions to, the transportation and storage of CWSF.

Jan 1, 1993

By L. J. Buter, D. J. Collins

Introduction FMC's Paradise Peak gold mine was discovered by staff geologists in July 1983. Located south of Gabbs, in western Nevada, the deposit contains about 11 Mt (12 million st) of ore grading at 3.6 g/t (0.105 oz per st) of gold and 129 g/t (3.75 oz per st) silver. It is estimated that the ore contains 34 t (1.1 million oz) of recoverable gold and 933 t (30 million oz) of recoverable silver. The 3.6 kt/d (4000 stpd) mill began operation April 14, 1986, just 18 months after Davy McKee completed a feasibility study and construction, and two-and-a-months ahead of schedule. It also came in about 10% under budget at a cost of about $100 million. Crushing Run-of-mine ore is delivered from the mine in 45-t (50-st) haul trucks to a 272-kt (300,000-st) capacity open air stockpile. Ore is reclaimed using 5 m3 (7 cu yd) front-end loaders that feed a 91-t (100-st) hopper equipped with a 610- x 610-mm (24- x 24-in.) grizzly. A 1.4- x 11-m (54-in. x 35-ft) apron feeder delivers ore from the hopper by way of a vibrating grizzly screen with 127 mm (5 in.) openings to a 1- x 1.3-m (43- x 51-in.) Rexnord jaw crusher. Crushed material is conveyed to a 1.8- x 4-m (6- x 14-ft) Link Belt vibrating screen equipped with a 50-mm (2-in.) manganese grizzly bar deck. Screen oversize is fed to a 1.7/0.6-m (5.5 ft) Rexnord standard cone crusher. Product from this crusher joins the -50 mm (-2 in.) screen undersize and is conveyed to a 136-t (150-st) surge bin. Three hydraulically driven belt feeders deliver ore from the ore bin to three 2 x 6 m (7 x 20 ft) Link Belt single-deck tertiary screens fitted with 6 x 25 mm (0.25 x 1 in.) slotted polyethylene screens. Screen undersize - -6 mm (-0.25 in.) rock - is conveyed to a 3.6-kt (4000-st) ore storage bin. Screen oversize is delivered by way of a conveyor to a 91-t (100-st) surge bin. From this bin, two belt feeders feed ore to two 1.7 m (66 in.) Rexnord Gyradisc crushers, which are in closed circuit with the tertiary screens. Design features include magnetic protection for tramp iron removal and sloping floors and pump sumps for ease of clean up. Dust scrubbers keep the working environment clean and in compliance with state dust emission regulations. Grinding Two 1 x 4.5 m (3.5 x 15 ft) belt feeders deliver ore from the fine ore bin to a conveyor belt that feeds it to the 5 x 7 m (16 x 22 ft) Allis-Chalmers ball mill. The conveyor belt is equipped with a Merrick weightometer. This controls feed rate to the ball mill by speed control on the hydraulic motors driving the feeders. The 2.6 MW (3500 hp) powered mill grinds 3.6 kt/a (4000 stpd) to an average grind of 85% -75 µm (-200 mesh). The mill is in closed circuit with four 660 mm (26 in.) Krebs cyclones. Three of these are normally in operation while one is a standby. Warman pumps feed the cyclones through a cyclone distribution manifold. The cyclone underflow returns to the ball mill, which has a 300% average circulating load. Mill discharge pH is 11, and that is obtained through pebble lime addition to the feed belt. Cyclone overflow is sampled using a Heath & Sherwood two-stage sampler. It then flows to a 27-m-diam (90-ft-diam) Eimco thickener. Thickener overflow is returned to the grinding circuit, while underflow at 50% solids is pumped to the leaching circuit. Grinding-circuit design features include a steeply sloped floor for ease of clean up, an open area over the pumps for maintenance accessibility, and a ball hopper with a self discharge bottom to speed ball addition. Other features include a mill liner handler and an air clutch that connects the mill motor to the mill.

Jan 12, 1986

By D. J. McCracken

During 1995, the estimated consumption of lithium minerals in the western world was 139 kt (153,000 st).This amounted to 18 kt (20,000 st) of lithium carbonate equivalent (LCE). Overall tonnage demand for lithium minerals increased by 10.8 kt (11,900 st) during 1995from 1994. From 1992 to 1995, overall tonnage demand has increased 62%, from 85.5 to 139 kt (94,240 st). There are four major producers of lithium minerals. Gwalia Consolidated in Western Australia is the largest producer of spodumene. It supplies high-grade spodumene concentrate, fine-spodumene concentrate, glass-grade spodumene and chemical-grade spodumene.Tantalum Mining (Tanco) of Manitoba, Canada, produces high-grade spodumene concentrate, fine-spodumene, concentrate and montebrasite. Bikita Minerals in Zimbabwe is the largest manufacturer of petalite. It supplies high-grade and container-glass petalite.

Jan 1, 1996

By E. D. Attanasi, M. W. Bultman

Most statistical measures of mineral exploration continued downward in 1986. Prospects in 1987, however, appear to have brightened for exploration as the overall economic health of the mineral industry improved. The Society of Economic Geologists (SEG) survey of US and Canadian firms documents the marked decline in US mineral exploration since the early 1980's. From 1981 through 1986, the total exploration expenditure by US firms declined by more than 73% (Fig. 1). Exploration expenditures by US firms declined by 66%%. US based professional exploration staffs were slashed by 70% (Fig. 2). Also, many firms have written off some reserves because of weak markets or have not delineated new reserves to replace production. The Canadian government reported that between 1981 and 1986 Canadian molybdenum re¬serves had declined by 30%, lead and zinc reserves by 20%, and nickel and copper reserves by 15%. The SEG survey also shows the immediate impact of the decline in the dollar on US exploration expenditures abroad. Between 1981 and 1986 the share of the exploration dollar spent by US firms outside of the country declined by nearly one-half and exploration acreage abroad declined by 69%. The downward trend of the last six years may finally be near the end as a leaner and more efficient minerals industry starts to gear up for a period of increased activity. An industry survey reported to Mine Development Bimonthly (Metals Economics Group) indicates that mining firms were expected to increase exploration expenditures in 1987 by at least 10% above 1986 levels. Worldwide expenditures for 1987 by companies covered by the report were expected to top $800 million. It is the first time since 1984 that an increase in exploration expenditures was expected. Also, the US Bureau of Land Management reported a 30% increase in new mining claims for fiscal year 1987 over fiscal year 1986. The bulk of the increase in claims was in states having intense gold exploration, particularly Washington and Oregon. Much of the optimism is undoubtedly due to the increases in metal prices that occurred in 1987. Some of these increases include gold, average price up about 20%; copper, average price up 24%; aluminum, average price up 26%; and nickel, average spot price up 20%. The SEG survey shows precious and base metals accounting for 89% of the exploration expenditures in the US in 1986, up 52% from 1981. The US Bureau of Mines estimates that 80% of US exploration activity in 1986 was directed entirely at gold (1986 Minerals Yearbook). Worldwide exploration plans indicate the continued dominance of gold exploration. New programs were announced for Ghana, Malaysia, and Indonesia. Major new exploration programs were also launched for lead-zinc sulfides in Morocco, platinum and palladium in northwest Brazil, rare earth minerals in Greenland, diamonds in Indonesia, and heavy minerals off-shore Australia. Significant gold discoveries were made at Angels Camp in Oregon; South Africa, near Potchestroom; India, in the Chitradgra district; Northern Ireland near Mt. Speerin; Chile, San Cris-

Jan 5, 1988

By Frederick B. Brien

For many years tin mining in Bolivia has been very important to the economy of the country. In recent years the tin content of the ore reserves has been steadily declining. An improvement in concentration efficiency is highly desirable in order to increase productivity from the present-low-grade mine ores and to allow retreatment of the many millions of tons of tailings from past operations, some of which equal the present ores in tin content. A number of investigators have been or at present are working on various phases or approaches to the problem. Gravity concentration is used in Bolivia today as it has been in the past to recover tin minerals from the mine ores. An objective of the work reported in this paper was to examine the possibility of treating present low-grade ores and sink-float tailings products, at a relatively coarse grind, in order to produce a higher grade feed material to the present gravity concentration plants. The possibility of using heavy liquids in cyclones to treat large tonnages with a minimum of outlay presented itself and is of particular interest since appropriate heavy liquids are available and with physical properties which lend themselves to simple recovery methods. Tests were carried out using a closed circuit laboratory cyclone assembly. It was desirable to determine the value of using the SG50 concept and Tromp curves for analyzing the cyclone concentration test results. The effects of entrained water on the behavior of ore particles in the cyclone were examined.

Jan 1, 1964