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By J. Duarte Neto, V. M. Torres, A. Viana, G. S. P. Pereira, P. M. Andrade

There are technical and commercial limitations to using high fluorine copper concentrates in industrial copper smelters. The presence of more than 1,000-ppm fluorine affects the sulfuric acid units generally integrated to copper smelters. Price penalties are normally applied to copper concentrates with high fluorine contents. Several process alternatives to resolve this issue were studied at the Companhia Vale do Rio Doce (CVRD) Technology Center, Santa Luzia, Brazil. These alternatives included modifications to conventional sulfuric acid plants so that they can use high fluorine concentrates; removal of fluorine-containing minerals by flotation using depressants; selective leaching of fluorine minerals; and sulfuric acid leaching of the copper concentrates. As a result of this research, a hydro¬metallurgical process to remove fluorine and upgrade copper concentrates was developed by the CVRD.

Jan 1, 1999

By Bernard Scheiner

A number of wells were drilled at two phosphogypsum stacks, one at P-21 owned by IMC and the other at Agrico's South Pierce Stack. Each well was sampled, and composites representing 5-ft increments were leached with synthetic rainwater to determine the extent of metal and nonmetal migration. To simulate what was occurring in the stack, composite samples were placed in a column, so that the column represented the stack in miniature form. Leaching experiments showed that both metals and nonmetals moved down the column when water was added to the top of the column. Data obtained from P-21 showed that with time the concentration of metals and nonmetals reached equilibrium values. The concentration of Ca, SO4, F, Si, and PO4 were -600 ppm,~1,500 ppm, 32 ppm, 14 ppm, and 22 ppm, respectively. Column leaching of South Pierce material, representing 0 to 55 ft of stack, showed that after 355 in. of water, the stack was near equilibrium values down to the 33-ft level. With continued addition of water, the portion of the stack at equilibrium would continue to increase and eventually reach the values observed for P-21. The test showed that the sulfate concentration of the effluent from the stack would never reach the USEPA standard value of 250 ppm. During the leaching test, it was determined that the permeability of the phosphogypsum in the columns was 0.000103 cm/sec. This number was used in the modeling. The data obtained from the leaching experiments cast some doubt on the practice of entombment now being practiced for closure of phosphogypsum stacks. The data clearly shows that with time, the amount of material leaching from the stack is low in concentration, with only the calcium and sulfate at higher levels. When a stack is closed at an existing operating plant, allowing rainwater to fall on the stack and capturing the solution in the existing pond system would eliminate the need for covering the stack, since with time the closed stack would continue to leach and at some point reach the equilibrium values of the P-21 stack. Entombment means that the leachable material in the stack will always be there and will require monitoring forever. Allowing rainwater to decontaminate the stack may be the best environmental solution to the problem.

Jan 1, 1999

By J. Brooks

The use and application of shotcrete for ground support in the Asia Pacific Region is as diverse as the countries that make up this region. This paper will attempt to describe the many methods used on selected projects within that region. The project description(s) will include project logistics, equipment, mix design, products and application methods utilized along with specifications and performance results (where available). The author will attempt to reach a conclusive opinion on the success, or nonsuccess, of the various shotcrete methods employed and the development of shotcrete within the Asia Pacific Region.

Jan 1, 1999

By John J. Sammarco

Mining has one of the highest annual average fatality rates among major US industries. Health and safety dangers have been inherent to mining since the early days of picks and shovels. Even though miners’ health and safety has improved over the years, mining is still one of the most dangerous occupations. Mining was traditionally a low tech industry. It is now driven by competitive pressures to go high-tech by using programmable electronics (PE) for machine control, atmospheric monitoring and material processing. The industry’s experience with the functional safety of PE is limited compared with other industries. Thus, PE is an emerging technology for mining that can potentially create or worsen hazards.

Jan 1, 1999

By D. Brunner

System simulation is an increasingly popular technique for analyzing and improving existing as well as newly designed underground mining operations. An engineering firm that specializes in simulation helped a major metals producer build a long-range planning model of an existing underground mine. Subsequently the team adapted this model to assess technology alternatives in the design of a new mine. The two models differ in the level of detail used for modeling the development process. This paper discusses the differences in approach between the models along with the experiences gained and challenges faced during the construction and use of the models.

Jan 1, 1999

By C. Bachmann, M. J. Laurila, A. J. Widenman, A. Klein

Elemental analysis of slurry streams using X-ray fluorescence (XRF) has long been employed. However, detector technology has limited the application of XRF devices. Using detector technology employed on NASA's Mars Pathfinder to analyze soil samples, Process Control, Inc. has developed an on-line analyzer to mount on a sampling system. The prototype XRF elemental analyzer was installed at Detroit Edison's Monroe Power Plant in January, 1998 and has been employed to monitor feedstock quality. A slurry system has been developed for flotation control. This paper describes the testing of the analyzer using the new, draft ISO standard for evaluating the performance of online analyzers (ISO/DIS15239).

Jan 1, 1999

By Robert Snow, Yingxue Yu, Howard Hanson, Patrick Zhang

One of the major current efforts by the Florida phosphate industry to reduce deep aquifer water consumption is to use 100% recycle water for flotation. This measure alone could save billions of gallons of deep well water annually. However, this also results in higher suspended solids (slimes) in flotation water, causing poor process performance particularly for amine flotation. Polymers could play a major role in allowing the industry to use high-turbidity recycle water for amine flotation without compromising its impact on the Florida economy. The enhancement of rougher flotation by polymers may also have potential. Most importantly, dramatic efficiency improvement may be realized by floating silica first. Adding polymer to flotation feed and/or water is perhaps the most economically viable way of reversing the Crago "double float" process, in order to reduce operating costs and increase phosphate recovery. This paper presents both laboratory and pilot flotation data showing the effect of different polymers on collector dosage and flotation recovery. There appeared to be an optimal range of polymer concentration beyond which the benefits do not offset the drop in phosphate recovery. The effect of poly mer is slime-level dependent. Pilot testing data show that the "Reverse Crago" process (floating silica first followed by phosphate flotation) can outperform the Crago process.

Jan 1, 1999

Inn mining communities throughout the western United States, cows have always been part of the landscape as they graze on surrounding rangelands. Until recently, mining companies regarded these animals as something to be kept off their properties — especially any freshly reclaimed lands. During the last few years, though, this situation has begun to change. Today, cattle can be seen in a handful of mine settings, moving up and down the slopes of mine tailings and waste rock. These animals are being used by several companies to do some of the reclamation work once performed by large earth-moving equipment, mechanical spreaders, rippers and seed drillers. This is because cows can contour slopes more naturally and produce and spread soil nutrients in ways that tractors and ripping machines cannot.

Jan 1, 1999

By Bernard A. Grand, Gary A. Almeraris

This project involves the reconstruction of a 1,100 ft. long by 75 ft. wide segment of an existing 4 to 5 track subway under Northern Boulevard in the Borough of Queens in New York City. The project includes widening the existing subway to permit the construction of new inbound and outbound subway (T1 and T2) ramps adjacent to and under existing operating tracks. The plan of the project is shown in Fig. 1. Existing tall buildings along the job site and a contaminated groundwater plume under an adjacent rail yard required construction of slurry concrete walls along the east and west construction limits. Groundwater cutoff across the north and south construction limits of the subway was achieved by jet grout walls built across the subway invert slab between existing track and third rails. The work involved dewatering the construction site to a depth of about 50 ft. below street grade. This is a four year project and includes extensive work to maintain and protect subway and vehicular traffic of over half a million commuters a day through the work area. The project cost was $160,000,000.

Jan 1, 1999

By Abdellah Chlk, Driss Msatef

Sedimentary phosphate ores are known for their relatively high specific surface area and porosity, which have a positive influence on their reactivity when used as fertilizer in acidic soils or in the manufacture of wet phosphoric acid and phosphatic fertilizers. However, these physical properties could have a negative effect on the behavior of these ores if dried. This effect has been studied on several phosphate ores samples by: the determination of mineralogical and textural properties of these samples, the determination of vapor water sorption isotherms, at different temperatures, from which the sorption heat has been calculated, carrying out several drying tests using a laboratory fluidized bed reactor under constant conditions, which showed important differences in drying rates and residual moistures.

Jan 1, 1999

By Clayr Alexander

Stillwater Mining Co. (SMC) is engaged in developing, extracting, processing and refining palladium, platinum and associated metals (PGM)from the J-M Reef. This geological formation is located in Stillwater, Sweet Grass and Park counties in southern Montana. Associated byproduct metals include rhodium, gold, silver, nickel and copper. SMC’s current mining operations are near Nye, MT. The company is currently developing a second underground palladium and platinum mine, the East Boulder project, about 21 km (13 miles) west of the Nye operations. A 5,650-m (18,550-ft) tunnel is required to gain access to the ore-bearing horizon (J-M Reef).

Jan 1, 1999

By A. Unal, R. L. Grayson

The use of radio frequency identification (RFID) technology to solve informational needs in isolated and restricted underground mining environments are reviewed, and the specifications of some of the past and currently available systems are presented. The advantages and disadvantages of using various frequencies, system configurations and specific components, including their construction standards and capability, are also discussed. The remaining challenges to the more widespread use of RFID systems for personnel and vehicle tracking are identified, and recommendations concerning the operating environment capabilities are detailed. Finally, the ultimate requirements for maintaining system integrity during and following a coal mine emergency are discussed.

Jan 1, 1999

By M. Prasad, G. M. Rao, A. K. Majumder, T. C. Rao

Froth flotation was employed to beneficiate a lean-grade siliceous rock-phosphate ore containing fluorapatite, the phosphate-bearing mineral. The main gangue minerals were quartz, iron oxides and aluminum oxides. After the rougher stage, four cleaning stages were required to upgrade the ore. The liberation size of the phosphate mineral was below 200 mesh, The reagent scheme consisted of commercial-grade sodium silicate and sodium oleate. The effect of reagent dosages, number of cleaning stages and pulp density on the efficiences of separation were studied systematically. A flowsheet was proposed for the processing of low-grade siliceous phosphate ore containing 12.1% P2O5, 55.36% SiO2 and 15.45% CaO. The flowsheet provided a useable phosphate concentrate containing 34.18% P2O5 and 14.20% SiO2 with a P2O5 recovery of 70.4% (the weight yield was 25.0%).

Jan 1, 1999

Steven F. Leer, president and chief executive officer of Arch Coal Inc. will be the master of ceremonies for the 12th Annual National Mining Hall of Fame Induction Banquet. The black-tie (optional) affair will be held at the Adam’s Mark Hotel on Sunday, Oct. 10 in St. Louis, MO. Six legendary leaders will be inducted at the ceremony. They will join 145 mining greats previously honored in the annual ceremonies. R. Joe Wagner, vice president for exploration and chief geologist of The Doe Run Co., St. Louis, will be the evening’s keynote speaker. His father, Richard Edwin Wagner (1898-1979), was inducted into the National Mining Hall of Fame in 1998 at the banquet in Phoenix, AZ.

Jan 1, 1999

By J. Kern, T. F. Torries

Identifying high value areas of unmined coal when large quantities of coal are available relative to annual markets is difficult because of the uncertainty of when the coal is to be mined. A GIS based methodology developed to value reserve coal in a producing coal region for the purpose of ad valorem taxation also identifies high value areas for mining investment. The methodology is unique in that it accounts for most mining, environmental, and market factors to determine when specific properties are to be mined. The methodology and data base are useful for directing regional exploration and acquisition activities toward most favorable areas.

Jan 1, 1999

By Joseph L. Petrillo

In July 1997, Kvaerner Environmental signed a unique contract with Echo Bay Alaska called the Transfer Risk and Accelerate Closure (TRAC). The contract called for Kvaerner to assume the responsibilities and obligations associated with closeout of the Alaska-Juneau (A-J) Mine. Kvaerner is an international engineering and construction company with global interdisciplinary experience in the mining industry and environmental remediation. Echo Bay’s requirements called for Kvaerner to: •Provide a fixed price for closure with no change orders. •Negotiate, prepare and implement a final closeout plan as outlined by Echo Bay. •Complete a closure program that exceeded current regulatory requirements. •Improve, expand and maintain a proactive public and community relations program. •Hire Echo Bay employees where possible. •Provide adequate performance guarantees and judicial relief of environmental claims.

Jan 1, 1999

By A. E. Koski

This paper describes the implementation of specialized software in mine planning at the Cleveland-Cliffs’ managed Empire Mine on Michigan’s Marquette Iron Range. The application puts together years of mining experience on the eastern end of the Marquette Range beginning in the early 1960’s. The Empire Mine, in its thirty-fifth year of production, uses the software to model a complex and highly variable low grade magnetite orebody, capturing the economics of mining and processing to the final product. With special attention given to geostatistical methods, the software is used for all geologic modeling, ore reserve estimation, ore control, pit design and short and long range planning.

Jan 1, 1999

By V. Svalbonas

The process of grinding mill quality assurance brings with it associated truths and myths. When the mill quality assurance process took its first great steps forward in the late 1970s and early 1980s, they were in response to the conditions existing, in our industry, at those times. In the late 1990s, we are faced with different conditions, and problems, and need fresh solutions. Yet the system developed for the early 1980s has produced no new approaches for the late 1990s, becoming instead more hardened and entrenched. This lack of development and actual resistance to research is now costing the industry significant amounts of money in late start-ups and useless scrap loss.

Jan 1, 1999

More than 5,300 mining professionals from around the world attended the SME Annual Meeting and Exhibit, March 1-3 in Denver, CO. Seventy three technical sessions highlighted innovative technologies and applications for the development of mineral resources. And the exhibit featured 421 companies worldwide and 632 exhibit booths. The 1999 SME Annual Meeting had 10% international attendance Professionals from outside the United States were guests at the first SME International Reception. Other meeting highlights included the Keynote Session. This pivotal session examined the international experience of North American-based companies. Speakers presented their perspectives on international explorations and operations. Keynote speakers included Robert Buchan, Chairman an( Chief Executive Officer, Kinross Gold; Dave Baker, Director Global Mining Project Management, Caterpillar; and Leendert Krol, Vice President International Operations Newmont Gold. Ihor Kunasz, 1998 SME President, made the introductory remarks.

Jan 1, 1999

By F. Hassan, M. A. Arafa

At El-Gedida iron ore deposits there is a block of about 30million tons neglected due to its higher sulfur content due to the presence of barite gangue minerals. From this bluk by magnetic separation dual concentrates of high grade iron concentrate (~65%Fe and total Sulfur of 0.26%) and the second concentrate is barite of (60.87% BaO and total impurities of less than 3%).

Jan 1, 1999