Search Documents

By George J. Allen, Laura A. Allen

Introduction This section of the text presents a general review of the different types of concentrate marketing contracts. Too often the marketing strategy is ignored in the design phase of the project and the producer is left to the mercy of the buyer. Many items such as concentrate grade, impurity levels and moisture content of the concentrate my enhance, or severely restrict the producers ability to make a profit it. Close attention should be paid to the design of the concentrator which can improve the quality of the concentrates, thus the ability to increase the rider of potential buyers can be enhanced. Difficult at best, is the position of the miner who only has one outlet available for its production. Obviously, the trade offs must be evaluated. For example, concentrate grade vs recovery and grind/filtering capacity vs moisture of the concentrate all must be weighted against freight cost to a potential buyer. In addition, the above considerations must be weighed against the capital cost to the miner. This chapter is intended to highlight important articles that are included in short and long term agreements and to give a new miner/producer some insight into hat my or my not add value to the product. Unless the miner sells the product directly to a consumer such as a gold, or silver producer, or to a large enough operation that has a totally intergrated system to make a finished product, most miners are forced to sell to buyers who ultimately will refine and market the product. Types of Contract Agreements There are many types of contract agreements just as there are colors in the rainbow, however, most contracts fall into three basic categories. (1) Smelter Schedules: Designed for the small producer, the odd lot of concentrate, smelter flux and precious metal ore. Albeit custom smelters are becoming fever by the day, because of pollution control requirements and financial difficulties, most remaining custom smelters have a smelter schedule. A smelter schedule is a posted list of charges and conditions that the smelter will buy material from a seller. Smelter schedules exist for copper, lead, zinc, silver and gold (Handbook for Small Mining Enterprises, Montana Bureau of Mines). (2) Short Term Custom Contracts: Large mine producers frequently use Short Term Contracts where the seller has the buyer frame a contract that is tailored to the sellers’ production. The short term contract my be as long as one year. A spot sale qualifes as a

Jan 1, 1986

By D. Nilsson, B. Aaro

To find out if there are any potential savings in "in-the-wall haulage for open pits," the Swedish companies ASEA and Kiruna-Truck in 1984 gave us financial support to study this solution in more detail. In the study, the use of in-the-wall haulage was studied for three hypothetical open pits with different sizes and shapes. Annual ore production rates also varied. A part of this thor¬ough study was published by the Swedish Mining Research Foundation (see Report F 8444, "The Use of Electric Trucks and In-the-Wall Haulage in Open-Pit Mining," in Swedish with an English Summary). Although in-the-wall haulage is of interest in some open pits, the local terrain is important for profitability. The authors do not think in-the-wall haulage is of any major interest for the mining industry. The following is a summary of some of the author's findings. To place the haul road in the wall is not of interest in open pits with declining metal contents in the bedrock. In such mines, the volumes from the haul roads will not yield reve¬nues. The cost per m3 for an underground haul road is much higher than for a haul road in the pit. This means that it is only of interest to place the haul road in the wall when mining gets deeper than about 50 m (165 ft). In-the-wall haul roads will reduce flexibility in the pit, and it will make necessary the use of smaller equipment with lower productivity and higher costs per ton. As Hustrulid, et al. show (Table 4), excavation savings of material hauled are very low, $0.10 to $0.25/t (0.09 to 0.27 per st). The extra operating cost, due to lower productive equip¬ment, will normally be much higher and thus destroy the whole idea with in-the-wall haulage. If electric trucks are profitable for in-the-wall haulage, it is normally also profitable to use electric trolley assist for trucks on the haul road in the pit. But the profitability of using electric power is different in different countries, and depends on the relation between the cost for electric power and diesel fuel. In the US, diesel fuel is inexpensive compared with electricity, but in a country like Sweden, diesel fuel is much more expensive. In most open pits, the trucks have to move a considerable distange from the loader until they reach a final haul road in the wall. A trolley line along such temporary haul roads will be exposed to flyrock. It is normally less expensive to perform rock support from the open pit than from underground ramps in the wall. In Fig. 8, Hustrulid et al. gives the impression that the underground haul roads will be very close to each other. This is seldom the case. Figure 1 shows a haul road in the wall. The haul road passes through each cross-section only once. Ar¬ranging a reliable dewatering and rock support system from only one underground ramp is probably impossible. Many more drifts are therefore necessary. In our report, we also studied what would happen if the final pit slope is increased by 5°, using underground drifts in the wall. Our conclusion was that the extra cost for drifts, rock support, pumps, etc. destroys the whole idea, and that it was better to accept a higher stripping ratio with the haul road in the pit and to use conventional low-cost open pit equipment. Finally, we think it is would be difficult to try to reduce the safety factor when determining the slope angle by moving the haul road in the wall. Minimizing the risk for pit wall collapse is also important with in-the-wall haulage, primarily because men and equipment will be working in the pit, but also to guarantee many accesses between the pit and the haul road in the wall.

Jan 1, 1989

By Dave Rogstad

The DART NC-1B Tunnel Project consists of two 5,100 m TBM excavated tunnels, a principal underground station, a partially completed future station, a surface station, and eight associated ventilation shafts and exit tunnels. This paper presents a case history of the project's construction, and will focus on six topics that give this project a unique and unusual history; the TBM excavation, two major differing site conditions, roadheader excavation, polyfiber reinforced shotcrete lining, the NATM design geometry, and a design/build type of contract.

Jan 1, 1995

By E. Topuz, M. J. McPherson, J. Banik

This paper summarizes the analyses of ventilation layouts for mines that experience both spontaneous combustion. The major focus is placed on the longwall coal mine layouts used in several countries. Each of the different layouts is modeled in the form of a ventilation network. The gob of a longwall panel is the most critical location for the occurrence of spontaneous combustion. Airflow leakage paths inside the gob are simulated by using a simplified grid-like network. Computer simulations with this model indicates that the W-system of ventilation is most effective in minimizing air leakage into the gob. Homer, the U-system of ventilation, with pressure balancing behind the face support line, is also found promising for longwall panels. The magnitude of air leakage into the gob is observed to change with the advance or retreat of bee, thus requiring appropriate balancing of pressure to maintain the leakage at a minimum.

Jan 1, 1995

By L. John Minnick

A revised and expanded edition of a previous paper** dealing with reactions of calcium and magnesium oxides and hydroxides with pulverized coal fly ash is presented. Lime-fly ash specimens were cured at constant temperature and subjected to X-ray diffractometry, differential thermal analysis, pozzolanic reactivity tests, and microscopical investigations. Bars of limefly ash were subjected to cycles of wetting and drying, and measurements of length change were recorded. A discussion of variations within and among types of lime and types of fly ash is presented. The nature of the pozzolanic reaction is reviewed, particularly as related to compounds which are used up and formed during the aging process. The relationship between the pozzolanic reaction and the resultant physical properties of the mixtures is examined.

Jan 1, 1968

By J. F. T. Agapito, C. E. Brechtel, M. E. Adam

Full-scale stopping and simulated over- cast structures were constructed in large opening (30 ft high by 55 ft wide) room and pillar excavations in an oil shale mine. The program was undertaken to develop construction techniques and to generate data on structure costs and leakage rates. Leakage rates were measured using both sulfur hexafluoride tracer gas and "brattice window" methods at varying differential pressures. The measurements were conducted before and after a full-scale face blast to characterize the effects of blasting on leakage, and blast air pressures were measured across the stoppings. The operating performance of different combinations of permanent and temporary stoppings was evaluated by developing an operating model for a two-panel oil shale mine. The operating performance for the different stopping combinations was then compared to the system cost to evaluate the overall performance.

Jan 1, 1987

By B. Boutilier, R. Mendoza

"First Majestic Silver Corp. (FMS) is a silver mining company founded in 2002 that operates exclusively in Mexico. It has six producing silver mines, one of which is the La Encantada silver mine (La Encantada) located in the state Coahuila. La Encantada is located near the southern United States border and 708 km (440 miles) north of the city Torreon.La Encantada is located in the Sierra Madre Oriental and is a high-temperature carbonate replacement deposit. Mineralization in La Encantada occurs in many different forms such as veins, chimneys, breccia pipes and reefs (mantos). Mineralization is mainly oxides of iron, zinc, lead and manganese, with high concentrations of sulfides at depth relating to two main intrusive events: the Milagros Intrusive and the La Prieta Skarn.Mining began in La Encantada during the 1950s with small vertical shafts, drifts and raises. It focuses on the high-grade silver zones using traditional hoists and extraction methods, before branching into two main separate mining camps: El Plomo and Penoles camp. Penoles, the previous owner, focused mainly on large ore bodies using post pillar cut-and-fill mining method to extract the higher-grade material. Due to the type of ground, irregularity of pillars, and rock conditions, large amounts of high-grade pillars had to be left in situ to ensure the stability of the excavations. The mined-out areas would then be filled with lower-grade material to assist in the stability of the secondary level. These room-and-pillar development entries were 2.5 m x 2.5 m (8.2 ft x 8.2 ft) and spaced every 10 m (32 ft), leaving a vertical pillar of 7.5 m (25 ft). First Majestic acquired La Encantada in 2006. After the acquisition of the mine, the company began the conversion of the surveying reference system from a local grid (Maria Isabel Shaft as 0,0) to the Nav27 coordinate system, and subsequently converted to the WGS84 coordinate system in 2015. Due to the extensive history of the mine, different areas were surveyed with different systems, causing significant challenges when designing the principal extraction levels, pillar heights and ramp locations. To overcome this difficulty, the entire mine was resurveyed and the old workings transposed to the new coordinate system, except for some inaccessible areas due to poor ground conditions or ground collapses. To further ensure pillar height and the safety of the mine workers, probe holes were drilled during the development process."

Sep 1, 2019

By Norman M. Junk

Following the wide-spread acceptance of ANFO as a useful, low cost blasting agent, studies have been made to adequately describe the physical and explosive properties of this material (1). As the quality of the AN blasting prill improved, reliability and sensitivity to initiation were greatly increased and many methods of priming were chosen from the standpoint of economics with little appreciation for the need to initiate so as to obtain the most efficient detonation. Under certain conditions, ANFO could be initiated with primers no more powerful than a No. 8 blasting cap (2). Research on primers for ANFO followed and it was demonstrated that this blasting agent was subject to extreme transient velocities upon initiation with wide variations in energy output depending upon the nature of the primer. For these reasons it was shown that powerful priming was economically justified (3). These studies helped to define the properties of an effective primer and the guides for its efficient use. In the vast surface coal mining industry, technological advances in earth moving equipment were paralleled by the development of larger and larger borehole drills (4). Even though ANM) was the major blasting agent used in this industry, investigations of priming techniques in these larger boreholes was almost non-existant. In 1962, Mr. Cleon Woolsey of Enos Coal Company disclosed to the industry that dramatic improvements in blasting production could be achieved with new priming and boostering methods (5). The research program at the Atlas laboratories was designed to explain these results and extend the study of initiation of ANFO with both high explosives and slurry explosives and to define the principles involved.

Jan 1, 1968

By James M. Stauffer

There are many types of filters designed to separate a solid from a liquid, including plate and frame presses, pressure leaf filters, gravity filters and vacuum filters. This discussion will be limited to continuous vacuum filtration and, specifically, to continuous rotary vacuum disc filters, drum filters and horizontal belt filters. The use of vacuum filtration can be advantageous in that: 1. The feed slurry can be delivered to the filter either by gravity or by a simple, inexpensive low pressure pump that only has to overcome the resistance of the feed piping system. 2. The filter equipment does not have to withstand high pressures. Consequently, a wide range of materials of construction, including plastic and fiberglas reinforced polyester (FRP), can be used in the fabrication. 3. After the form time, the filter cake is exposed to the atmosphere and the cake is accessible for further operations such as mechanical or physical dewatering, washing, and sampling on a continuous basis. 4. The discharge of the dewatered solids is continuous for directly feeding to the next operation; for example, a dryer. 5. Various methods of discharge can be fitted to the filter to effect optimum discharge of the dewatered cake solids. The principal of operation of a vacuum filter, regardless of type, is basically the same. The filter incorporates a filter medium supported on a drainage system and arranged so that the mixture to be separated (feed slurry) can be introduced to one side of the filter medium on which the solids are trapped and through which the liquid (filtrate) flows due to the applied vacuum.

Jan 1, 1979

By A. Ghosh

Commonly used predictors of ground vibration from blasting, being linear in log-log plot, do not model the underlying physics of wave attenuation. Amplitude of the wave decays with distance due to geometrical spreading and inelastic attenuation producing a nonlinear carve in log-log scale. The nolinear decay of seismic waves has also been observed from non-explosive sources, such as, pile driving, drop hammer, traffic, etc. The improved predictors, by explicitly taking these two mechanisms into consideration, model the data trend extremely well at all distance ranges. Actual field data from different studies have been used to validate the improved models.

Jan 1, 1991

By David R. Hargis

Large-scale groundwater withdrawals are necessary to depressurize a confined aquifer system allowing the dry open-pit mining of the overlying phosphate ore. The extent of the existing and planned groundwater development led to the establishment by the State of North Carolina of Capacity Use Area No. l. Groundwater use in the Capacity Use Area is regulated by a permitting system. A two-dimensional finite-difference ground- water flow model was developed for North Carolina Phosphate Corporation. The aim of the model is to aid the Corporation in matters relating to permitting by serving as a predictive tool. The model can be used to project regional water level impacts resulting from various scenarios of depressurization pumping.

Jan 1, 1983

By Rodolfo V. de la Cruz

The stresses in the materials surrounding an underground opening are dependent upon the virgin stress field, the geometry of the opening and changes in boundary conditions as mining progresses. For most underground openings especially in coal mines, roof bolts are installed to help stabilize the opening. While most parameters in roof bolt design and installation have been thoroughly investigated, the effects of the initial stress field on the effectiveness of roof bolts have not been recognized. This paper summarizes the results of investigation of the effect of the initial stress field on the performance of mine roof bolts. Roof bolt installations are duplicated in the laboratory utilizing conventional roof bolt frame, commercial roof bolts and shells, mine torque wrench and encapsulated rock specimens for anchorage. A special and primary feature of the laboratory set-up is the addition of a loading system for generating stresses at the anchorage specimens. For this preliminary study, different levels of hydrostatic stress fields were induced at the anchorage specimen, instrumented roof bolts were installed in the usual manner, and the bolt load loss-with-time observed. Statistical analysis of data showed that the stress field at the anchorage horizon has a considerable influence on the performance of mine roof bolts, i.e. the higher the stress field, the higher the anchorage efficiency. From this observation, methods of improving the performance of mine roof bolts utilizing new shell designs and methods of installing them are suggested.

Jan 1, 1978

By M. P. Smith, C. Hughes-Narborough, Y. T. Man

"Money and reputations can be lost in bad projects. Causes of bad mineral processing projects include poor contract definition and purchase of equipment without adequate test work. However, the root cause of many of the problems that can lead to bad projects is not any inanimate object, bad weather or catastrophic natural event but the people working on the projects. Because the people are so critical to the success of a mineral processing project, one must have suitably qualified and experienced people (SQEP) in all key positions. Characteristics that define SQEP include people who have successfully executed projects of similar size before; have undertaken projects treating the same minerals and producing the same valuable products and people who are familiar with designing, operating and implementing the required technologies and unit operations.To minimize the likelihood of future bad mineral processing projects, five recommendations are put forward in relation to the people aspect of a project.1. Attempt to retain SQEP during any down turn in the mining economic cycle so thatthe knowledge and experience can be kept within the industry.2. Increase the effort in attracting young people into the industry and retaining them.3. Set up robust training program to give young professionals a firm foundation of what real life projects and operations are like.4. Provide mentoring and continuous training for people after they have completed their formal graduate training program. Their career progression should be appropriately monitored and controlled.5. People working in projects must be exposed to as many detailed design and other finer issues as possible so that they can comprehend the amount of work required to deliver a project successfully."

Aug 1, 2016

By M. L. Harris, J. Organiscak, S. Klima, I. E. Perera

"The Pittsburgh Mining Research Division of the U.S. National Institute for Occupational Safety and Health (NIOSH) conducted underground evaluations in an attempt to quantify respirable rock dust generation when using untreated rock dust and rock dust treated with an anticaking additive. Using personal dust monitors, these evaluations measured respirable rock dust levels arising from a flinger-type application of rock dust on rib and roof surfaces. Rock dust with a majority of the respirable component removed was also applied in NIOSH’s Bruceton Experimental Mine using a bantam duster. The respirable dust measurements obtained downwind from both of these tests are presented and discussed. This testing did not measure miners’ exposure to respirable coal mine dust under acceptable mining practices, but indicates the need for effective continuous administrative controls to be exercised when rock dusting to minimize the measured amount of rock dust in the sampling device IntroductionTwo recent regulations have modified operators’ rock dusting schedules in order to meet compliance standards. First, the 80 percent incombustible requirement in intake entries has increased both on-section and out by the- section rock dusting. Secondly, the recent change to the respirable dust regulation has increased the number of respirable dust samples taken per sampling cycle. Previously, when only five samples were needed bimonthly, rock dusting could be scheduled to not interfere with the respirable dust sampling schedule.The significant number of samples now required under new regulations, combined with the need to maintain 80 percent total incombustible content in active mining areas, require the schedules for respirable dust sampling and rock dusting to overlap. Although rock dust is considered a nuisance dust in relation to U.S. Mine Safety and Health Administration (MSHA) sampling, these overlapping schedules raise concerns about the amount of rock dust that potentially is included in the sample. Additionally, the respirable dust maximum was lowered from 2.0 mg/m3 to 1.5 mg/m3 effective Aug. 1, 2016, increasing concern that rock dust contamination may be an issue (MSHA, 2016). Currently, the acceptable practice is to apply administrative controls such as keeping the miners upwind during rock dust application, or to schedule rock dusting during a maintenance shift when the number of miners present is lower."

Jan 5, 2017

By Donna L. Boreck

Introduction Coal has been mined in the western United States since the mid-1800s. The resource is abundant in the West. Despite recent economic conditions, it remains an important part of the nation's energy warehouse. Many of the seams that comprise the western resource base are thick, some exceeding 61 m (200 ft). Multiple, closely-spaced seams or thick coals that split into two or more minable seams are also common. Historically, subsurface development recovered from less than 15% to 50% of these deposits (Matson and White, 1975). This resulted in a substantial loss of inplace reserve due to the limited height that could be mined using the available technology. In an effort to increase future recovery from such deposits, the US Bureau of Mines analyzed the potential for incorporating three thick-seam mining methods into western coal mines. These methods are high-face longwall, multislice longwall, and longwall caving. They were developed in Europe and are being used to mine thick coal seams in Europe and Asia. One aspect that will determine their success in the US is the geology of the individual deposit; namely, are the methods adaptable to the geologic conditions characteristic of western coal? This paper analyzes some of the geologic factors that would affect development of thick or closely-spaced seams using these mining methods. Occurrence of thick and closely-spaced seams Since mining conditions and methods differ around the world, a thick seam is often defined as a seam whose total thickness cannot be extracted using the available equipment. In the western US, the maximum extractable mining height is about 4.3 m (14 ft). For this research, a thick seam was defined as a minable seam 4.6 m (15 ft) thick or more. Since one of the seams is usually lost using standard mining methods, closely-spaced or split seams were also addressed. These were defined as two minable seams 1.5 m (5 ft) thick or more separated by 9 m (30 ft) of interburden. Thick or closely-spaced coal seams are common in the West. Their importance has not been documented due, in part, to the methods used to measure resources. In the past, all reserves greater than 1.1 m (42 in.) thick for bituminous seams and greater than 3 m (10 ft) thick for subbituminous seams were grouped together and were differentiated only by rank. Further differentiation by seam thickness or minability was not done. For this reason, reserve figures for thick or split seams are difficult to determine. By analyzing available published resource data, Ferm and Muthig (1982) addressed thick seam resources. They estimated a resource of 90 Gt (99 billion st) of coal (16% of the Western resource base) in seams 4.6 (15 ft) or greater at less than 610 m (2000 ft) overburden. Yet, a later study of Pierce and others (1982) on one thick seam deposit in the Powder River Basin estimated a resource of 103 Gt (113 billion st). Pierce (1986) reported that the overburden reached a maximum of 731 m (2400 ft). The resources in this single deposit exceeded the 90 Gt (99 billion st) total projected for the entire western US by 12.7 Gt (14 billion st). Due to such differences, this author chose to look at reported occurrences of thick or closely-spaced minable seams in place of resource figures, to verify the need to research thick seam mining in the West. An occurrence was defined as an isolated site where a thick seam or two or more closely-spaced seams were reported. The occurrences were derived from published material - mostly mine descriptions, measured sections, coal exploration logs, and oil and gas logs. Due to time constraints, the reserves associated with each occurrence were not determined. All data points were random. The analysis was limited to occurrences in Colorado, Wyoming, and Utah. Although source material available to the author was limited to general coal summa-

Jan 3, 1988

By M. P. Roy, P. K. Singh, A. K. Mishra, Ashish K. Vishwakarma, Vivek K. Himanshu

Ground vibration is one of the major hazards produced by rock-blasting operation. The accurate prediction of vibration is necessary for designing controlled blasting parameters. The existing vibration predictors consider maximum explosive charge weight per delay and distance as the parameters responsible for ground vibration. These predictors are based on the assumption that the geometrical parameters of the blast will be constant for a site. However, the mining sites with bigger production targets have varying geometrical parameters to suit the excavator utility. Accordingly, the other blast design parameters will also have an impact on ground vibration intensity. A principal component analysis is a dimension reduction technique. This technique along with multivariate logarithmic regression has been used in this paper to predict the ground vibration. The technique has classified the blast design parameters into four principal components. The regression with the scores from these principal components has been carried out. The evaluation of the model performance of predictors along with the existing empirical predictors has been carried out using R2 and RMSE values. The evaluation suggests that the predictor with logarithmic regression followed by principal component analysis gives better performance with respect to the existing empirical predictors.

Jul 30, 2022

The most important event affecting the United States coal industry in 1993 was the strike by the United Mine Workers of America (UMWA). This was a series of selective strikes, beginning with a strike against four Peabody Holding affiliates on Feb. 2, following unsuccessful contract negotiations between the UMWA and the Bituminous Coal Operators' Association (BCOA). Although that strike ended on March 3, the failure to reach a new contract agreement led to walkouts at several Midwestern mines on May 10. During the summer, the strike expanded to include mines of 13 companies in seven states including Ohio, Pennsylvania, Illinois, Indiana, Kentucky, Virginia and West Virginia. About 17,000 miners were idled during the strike. As the prospects for a settlement diminished, the Secretary of Labor appointed a federal mediator. The mediation resulted in a five-year contract. In addition to increases in wages and pensions, it was agreed that 60% of new job openings would be filled by laid off and active UMWA miners. In return, companies won the right to establish more flexible work rules and scheduling of miners. While some health care benefits were expanded, the agreement established a new health care system that was designed to reduce costs. Preliminary Energy Information Administration (EIA) data indicate that US coal production fell by 5% in 1993, to 859 Mt (947 million st) (Table 1). The strike was one of the primary causes of the decline in production. Another significant cause was a 27% decline in coal exports. Also, a very small displacement of domestic coal production resulted from a rise in coal imports.

Jan 1, 1994

By William R. Bush

This paper is a presentation of findings based upon an econometric model of the world zinc industry. The model was developed as a simple but useful aid for long-run forecasting and planning purposes. A structure was developed for both simulating real zinc price effects on production and consumption, and for forecasting long-run annual zinc prices and supply/ demand levels. Moreover, a methodology is provided to incorporate the effects of: (1) historic technological advances in zinc supply, and (2) the development of the competitive plastics industry. Finally, reduced form equations are used to generate ex post forecasts to evaluate the model's performance.

Jan 1, 1979

By Walter C. Labys

This paper reports on recent modeling efforts to analyze the eastern U.S. steam coal market with a cross-sectional econometric as well as a quadratic programming approach. The background to coal modeling is examined first. The particular aspect of the steam coal market to be modeled are then presented and the corresponding coal model described. Both empirical results and rigorous mathematic pertubation analysis are presented. Conclusions are then drawn regarding potential modeling applications in the policy area.

Jan 1, 1979

By P. Eger

Minnesota contains a major low- grade copper-nickel sulfide resource within the Duluth Gabbro Complex. Several companies have actively explored this resource. Open pit mining would be required to develop portions of the resource, and as a result, large quantities of sulfide-bearing lean ore and waste rock would be stockpiled. Although the problems associated with high-sulfide tailings and acid mine drainage are well documented, the leaching characteristics of low-grade mineralized stockpiles must be understood for environmental impact assessment, siting, and planning. The Minnesota Department of Natural Resources and AMAX have cooperated in a research program to study leaching and revegetation -of test stock- piles, Six small (1600 'tons) stockpiles were constructed at the MINNAMAX Project Site and they range in composition from 0.29 to 043 g % copper, 0.075 to 0.09% nickel, and 0.6 to 1.45% sulfur. Two of the stockpiles were covered with mineral soil, one was covered with topsoil, and three were not treated Revegetation plots were established on the piles which received a soil cover. Leachate samples and flow measurements were collected at the base of the piles. Initial results indicate that metal concentrations in leachate samples range from 10 to 10,000 times the concentrations found in the streams of the area. During the first growing season, the test pile covered with topsoil yielded 30% less water than untreated test piles. No reduction in yield was observed for the piles that were covered with the less fertile mineral soil. First-year vegetative growth, expressed as biomass, was four times greater on the-topsoil pile than on the mineral soil piles. The long-term effects of vegetation on leachate quantity and quality continue to be investigated.

Jan 1, 1980