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By Judson H. Whitman

To evaluate intelligently and to market a source of rare earth raw material, it is necessary that the producer understand the requirements of the processor and the manner in which these requirements effect the value and salability of his product. This paper will be an attempt to aid in such an understanding. The majority of rare earth processors are primarily chemical companies, not mining or metallurgical companies, as the complexities of the processing procedures are' much more chemical in nature than metallurgical. The rare earths and the rare earth industry are normally divided into two groups - the ?light? or cerium group and the ?heavy? or yttrium group. They are so named because cerium and yttrium are the most common elements in 'heir respective groups and are so divided on the basis of mineralogical and chemical characteristics. The dividing line of the two groups is not rigidly fixed but usually is considered as being between samarium (atomic number 62) and europium (atomic number 63). Although the two groups are quite similar, processing procedures differ significantly, hence most processors tend to specialize in one group or the other. There is, however, a growing tendency toward participation in both groups.

Jan 1, 1960

By R. A. Hevia

Florida Power and Light is the fifth largest investor-owned electric utility in the country. It has a service territory that covers 35 counties, or 28,000 square miles, 2.5 million customers, and serves 5.6 million people. The total installed capacity is 13,470 MW, generated by four nuclear units, 36 oil and/or gas fired units, and 48 gas turbine units. Traditionally, FPL has been an oil-based utility. In 1979, this dependency on oil became obvious when 42 million barrels of oil were burned during the year. At that time, it was also projected that, based on the current estimates of customer growth and available generation capacity through 1990, FPL's residual fuel oil consumption would increase from the 1979 level of 42 million barrels (6.7 million m3) per year to approximately 55 million barrels (8.7 million m3) per year by the mid-1990's. Concern over this was further aggravated by the fact that it was difficult to estimate both the price and quantity of fuel oil that would be available over the next decade since changes in the world market, decisions by oil producers and refiners, and international political developments would all affect the availability of oil. Also, at that time, the price of residual fuel oil had increased drastically, and there was no reason to think that these prices would soon stabilize. Thus, oil back-out became a primary objective of FPL and since then, FPL has been actively investigating ways to decrease fuel oil consumption.

Jan 1, 1985

By T. R. Ellis

"In August 2013, the Appraisal Practices Board of the U.S. Appraisal Foundation issued its “APB Valuation Advisory #4 - Identifying Comparable Properties,” which contains analysis and examples that may suggest a broader meaning of the term “comparable properties” than is current convention in real property value appraisal in the United States and internationally. The advisory is directed at the appraisal of real property of all kinds, including interests in mineral properties, as indicated by the inclusion of two mineral property appraisal papers in the appendix that lists suggestions for further reading.This paper firstly reviews as background the historical meaning of a comparable property, with its perceived constraints, against real-world examples of transacted mineral properties that are adjusted to subject properties to provide market value indications. The advisory’s findings are then examined and evaluated as to whether they may influence and benefit the work of mineral property appraisers, particularly in situations where their sales comparison analyses may be challenged. The conclusion is that the combination of constraints that the advisory’s findings specify for use of the term “comparable” will for mineral properties be met infrequently or rarely. As a result, mineral property appraisers are advised to avoid using the terms comparable or “comp” when referring to transactions of mineral properties that they analyze to derive data for appraising the value of their subject mineral properties. IntroductionA mineral property appraiser rarely finds a sale of a mineral property that meets the literal meaning of the term “comparable sale,” by being directly comparable to the subject property of the appraisal in all factors of significance in the determination of the value of the property interest being appraised. Real estate appraisers have long used a more liberal interpretation of the meaning of comparable sale and its commonly used abbreviation, “comp.” Real estate appraisers compare sales to their subject property on the basis of price per hectare or acre of land and price per square meter or square foot of building floor area. Adjustments totaling to within the range of +30 to -30 percent from the sale property to the subject, before factoring in the property area, have generally been viewed as appropriate for the sale to be considered a comparable sale."

May 1, 2016

"A commercially available through-the-earth (TTE) communications system was evaluated at an active underground longwall mine in West Virginia. This TTE system uses electricfield (E-field) sensing to send text-based communications through two separate antenna arrays connected in parallel. Each antenna array is composed of interconnected, grounded metallic rods or other such structures. Two-way communication between subsurface locations was investigated in this study using various antenna configurations. This field study was conducted as a part of a larger multisite evaluation of available TTE systems in an effort to determine their operational sensitivities. IntroductionWireless, through-the-earth (TTE) communication technology is designed to achieve point-to-point communication through solid strata using very low frequency (VLF) and ultra-low frequency (ULF) electromagnetic waves. Using this approach, communications are established without the need for intermediary communications infrastructure. As a result, TTE systems have the potential to provide reliable, robust communications between surface and underground personnel. Exploration into the use of TTE technology for this purpose dates back to the 1920s (Jakosky and Zellers, 1924; Pittman, Church and McLendon, 1985), but U.S. permissibility requirements slowed the development of TTE equipment for widespread implementation (Durkin 1980; Pittman, Church and McLendon, 1985). One of the primary challenges in producing wireless TTE communications is the counteraction of signal attenuation when propagating through solid strata (Barkand, Damiano and Shumaker, 2006; Wadley, 1949). The long wavelengths of TTE transmissions make them well-suited for reducing the rate of attenuation. However, even when operating within the VLF to ULF range, the performance of TTE systems is still affected by geologic and anthropogenic factors (Geyer, 1973; Geyer and Keller, 1976; Geyer, Keller and Ohya, 1974; Jakosky and Zellers, 1924; Large, Ball and Farstad, 1973). Although commercially developed TTE systems have demonstrated the ability to communicate in a variety of conditions, their range and performance have been highly varied (Barkand, Damiano and Shumaker, 2006; Geyer and Keller, 1976; Geyer, Keller and Ohya, 1974; Ilsley, Freeman and Zellers, 1928; Jakosky and Zellers, 1924; Yenchek et al., 2012)."

Sep 1, 2016

By R. Rodgers

The Pinto Valley Concentrator of BHP Copper Inc. restarted its sulphide mining operations in September 2007 to produce copper and moly concentrates. During the plant production ramp up, the copper/moly circuit quickly reached the copper grade and recovery targets, but the production and quality of the moly concentrate continued to be a challenge. Even though several improvements in the moly circuit were completed, the final moly concentrate did not meet contractual specifications. After reviewing several options to improve grade and reduce contaminants, the installation of three flotation columns was chosen. The column design and construction were done utilizing in-house craftsmen and engineers. Ten days after commissioning, the columns successfully reached a steady operation and began producing moly concentrate to the required specifications, that is, high moly tenors and low copper and iron content. In this paper, the operating parameters, mass balance, design, installation, commissioning and operation of the new flotation columns will be discussed.

Jan 1, 2010

By G. Bonifazi

Certain deposits of incoherent materials which are near the surface and exploitable by open-pit mining may be characterized in real time before they are mined through an analysis of ground-surface imagery. If the slice to be stripped is not overly thick, in fact, surface texture and color properties may be extrapolated to its entire thickness. Image analysis techniques to process ground surface images acquired in situ (or in the laboratory shortly after their acquisition) which yield pattern vectors representative of RGB color component distributions and HSB texture parameters have been developed. The techniques were applied to a mineral sandy ore deposit containing three different lithotypes. Geostatistical analyses showed that the data used to characterize the lithotypes were reliable. The correct recognition of the lithotypes was carried out using a multi-barycenter classification algorithm. Such in situ image-analysis procedures open the way to the proper selection of the ore to be mined, or the proper way for run of mine (r.o.m). processing, or the appropriate blend to be processed before or at the same time as the mining process itself is enacted.

Jan 1, 1999

By Jose M. S. Ramos

This paper describes the slope stabilization procedure at Cauê Mine, Companhia Vale do Rio Doce - CVRD, Itabira, State of Minas Gerais, Brazil. Cauê Mine, is a large open pit, to produce about 41 million tons of iron ore during 1974, and an intensive program of investiga Lion was carried out to provide the basic data for stabilizing its slopes, The ultimate rock slope in the W area will be about 400 m high with dipping angles decreasing gradually from top to bottom of the pit. The investigations started in 1969 and since then many geologists and engineers, from both CVRD and Geotécnica S/A., assisted by international consultants, have given their contribution to the achievement of solutions. It is hoped that this paper may contribute to the slope stability of other mines in tropical climate.

Jan 1, 1974

Underground instrumentation and observations at longwall panels have demonstrated that the growth of main roof causes an extremely high roof weighting on the shields. It can sometimes result in catastrophic effects on the support when the roof weighting intensity far exceeds the support capacity. In this paper, a comprehensive study was conducted on characteristics of main roof breakage and its effects on shields at different locations, based on the monitored shield data, theoretical analysis, and finite element analysis. With the help of theoretical analysis and numerical modeling, stress distribution and redistribution in the main roof were analyzed in detail to define main roof failure modes and understand the maximum roof weighting intensity imposed on the shields. From this study, it was found that the effects of main roof breakage on shields are chiefly related to the shield initial setting condition and the final failure mode of the main roof.

Jan 1, 1994

By Khosrow Badiozamani

Operating mines in Wyoming and Montana, which are generally characterized by shallow overburden and thick coal seams, are faced with reclamation problems which are unique to this area. Unlike the eastern or midwestern mines, removal of thick coal seams and lack of sufficient overburden creates overburden deficiencies that require careful evaluation prior to mining to insure compliance with regulatory requirements. Computer models and computer graphics can assist in such evaluation where appropriate alternatives can be selected which satisfies both the regulatory requirements and minimizes cost. This paper presents one such model used in evaluation of backfill requirements for restoration of surface and ground water regimes, restoration of mined-out areas to the approximate original contour, and the blending of the mined-out areas to the surrounding topography.

Jan 1, 1981

By Bert C. Morrison

In 1961. American Smelting and Refining Company was conducting exploration for lead in southeastern Missouri using several geophysical methods. Electrical methods were used in almost every hole drilled during this period. These methods met with only limited success, with one exception. This paper deals with that exception: An Electrical Potential Method used at a single hole to indicate direction to better mineralization. This method was notably successful in the program.

Jan 1, 1970

By F. L. Pirkle

A heavy mineral deposit about 1.6 km (1 mile) in length, 0.13 km (0.08 mile) in width and averaging about 3 m (10 ft) in thickness is exposed approximately 130 km (80 miles) east of Denver, along Interstate 70, in Elbert county, CO near the town of Limon. The deposit is exposed in a geomorphic feature known locally as Titanium ridge. The dominant heavy minerals, accounting for about 70% of the total heavy-mineral suite by weight, are ilmenite, garnet and zircon. The mineralized zone appears in a series of visually interpretable facies that are stacked vertically and represent subtidal, forebeach, backbeach, washover fan and aeolian depositional environments. These paleoenvironments are analogous to depositional environments represented by a modern heavy-mineral bearing facies tract on St. Catherines Island, Ga. Thus, Titanium ridge provides evidence that heavy-mineral accumulation models for late cenozoic deposits in the Georgia and Florida coastal plains are applicable to heavy-mineral deposits of the Western Interior subsurface and, by implication, the Western Interior Seaway, extending from Mexico to the Canadian Arctic.

Jan 1, 2012

By M. L. Harris, I. Zlochower, M. J. Sapko, I. E. Perera

Experiments conducted with limestone dusts and dolomitic marble dusts have indicated that when rock dust is wetted and subsequently dried, it becomes a solid, non-dispersible cake. However, in order to be effective, rock dust must be able to disperse as individual particles to inert. To counteract this, rock dust manufacturers created treated rock dusts that will resist caking after moisture exposure. National Institute for Occupational Safety and Health (NIOSH) researchers conducted a series of laboratory-scale experiments on four base rock dusts and their treated counterparts to assess the effectiveness of various anti-caking additives after being exposed to moisture and then dried. The dusts were exposed to moisture using humidity cabinets having a high relative humidity (99% RH) and by also exposing the rock dust bed to water through bottom wicking. The dusts were then evaluated for dispersibility after drying using the NIOSH-designed dust dispersion chamber. The anticaking additives were different concentrations of stearic acid, oleic acid, and xylene-based surfactants. All results were compared to a reference rock dust used to conduct large-scale experiments in the Lake Lynn Laboratory (LLL), Fairchance, PA. When the untreated dusts were dried after exposure to moisture for one day, no dispersion was measured. However, rock dusts treated with anti-caking agents were readily dispersible even after exposure to moisture for six months. This report details the analysis and characterization of anti-caking additives using the NIOSH-designed dispersion chamber and the 20-L explosion test chamber. INTRODUCTION In order for a coal dust explosion to propagate, five elements are required. In addition to the fire triangle in which three elements are necessary to sustain a fire—fuel (coal dust), heat (ignition source), and an oxidizer (oxygen in air)—a combustible dust explosion requires dispersion of a dust cloud (pressure wave) and confinement of a dust cloud (underground mine entry) (1). Coal dust explosions can originate anywhere in a mine. For example, when a small volume of a flammable methane and air mixture is ignited in a closed end, the high-temperature gases rapidly expand to create a pressure wave, sometimes referred to as a “pioneer wave,” that may steepen into a shock wave as it propagates away from the ignition source. The shock wave produces a wind that disperses the dust preferentially from any elevated and exposed surfaces (roof, ribs, belt structure, cribbing, etc.). Factors that are known to affect the intensity of an explosion are the dust particle size, the location of the dust within the entry, the dust dispersibility, and the volatility of the coal dust (1). Particles less than 75 μm (< 200 mesh) in size are most reactive (2). Dusts that are located on the roof, ribs, and elevated surfaces are more readily dispersed than dusts on the floor. Therefore, application of quality rock dust in sufficient quantities is essential to inert coal dust and to prevent continued flame propagation. 30 CFR 75.402 and 75.403 require 80% total incombustible content be maintained within 40 ft of the face, and 30 CFR 75.2 defines rock dust acceptable for use in underground coal mines. It also defined that “when rock dust is wetted and dried, will not form a cake”.

Jan 1, 2019

By F. L. Pirkle, W. C. Bagby

"In his 1989 book, The New Realities, Peter F. Drucker, Clark Professor of Social Science at Claremont Graduate School, Claremont, CA, stated: “Information is data endowed with relevance and purpose. Converting data into information thus requires knowledge. And knowledge, by definition, is specialized” (p. 209).The discipline of mineral valuation is knowledge-based and requires a mineral valuer to collect, analyze and interpret data that are material to a mineral-valuation assignment. In so doing, the valuer turns the data into information (data come first, followed by information as determined by the mineral valuer) for use by the client (from whom the valuer obtained the mineral-valuation assignment) and other intended users. The valuer uses his or her experience and education (each valuer’s knowledge base) supported by a foundation built upon competency, materiality and transparency, the three pillars of mineral valuation (minerals valuation, mineral-property valuation).The International Mineral Valuation Standards Template (IMVAL Template), third edition dated May 2018, defines mineral valuation as: “The estimation of the value of a mineral property in money or monetary equivalent. The word ‘valuation’ can be used to refer to the estimated value (the valuation conclusion) or to refer to the preparation of the estimated value (the act of valuing)” (p. 14).Furthermore, the IMVAL Template clearly separates valuation from evaluation: “The template deals with valuation, which is distinct from evaluation. The distinction inherent in these defined terms is that valuation addresses the estimation of value of a mineral property, whereas evaluation addresses the broader assessment of a mineral property for an investment decision (p. 2).”This is an important difference because the minerals industry commonly makes investment decisions using feasibility studies to evaluate a proposed mineral development and production project. The purpose of such investment-decision analysis is distinctly different from valuation of a mineral property, no matter where that property lies upon the mineral explorationdevelopment- production-reclamation timeline (Fig. 1). Valuation involves terms such as market value, just compensation, fair value, etc., whereas investment-decision analysis is concerned with the economic viability of a given proposed project. Although feasibility analysis and market valuation can both use discounted cash flow (DCF) analysis as a tool, the formulation of the DCFs and their interpretation are different."

Nov 1, 2019

By T. P. Weldum, W. Conger

"These studies address the relationship between mill media sizing and its grinding efficiency. Starting with the results from a review of the literature, the issues of initial media sizing for a new ball milling circuit, and then optimal media sizing for an existing milling operation, were studied. The Functional Performance parameters “Mill Grinding Efficiency” and cumulative “Mill Grinding Rates” from both plant and test-scale equipment were used, and provide valuable new insight into this topic. A plant media sizing diagnostic tool is presented, as are newly developed testing equipment and evaluation methods, and recent case studies. REVIEW OF MEDIA SIZING LITERATURE For a plant metallurgist to answer the question “How can I maximize plant profit by manipulating this grinding circuit variable?” she must know what effect the variable has on grinding circuit efficiency. Despite the significant cost of grinding media and its potential effect on production capacity, the ‘best’ media sizing remains ill-defined for any given ball mill circuit in the industry today. The underlying reasons for this will be discussed. But the importance of this issue drove Metcom and its industrial partners to take on the challenge of how to engineer the ball charge for an existing grinding circuit. In the absence of any proven method, the first step was a review of the literature. Sponsored by Cleveland-Cliffs, Inc., a broad review of the literature was undertaken, producing “The Effect of Media Sizing on Ball Milling Efficiency” (McIvor, 1997). Among hundreds of publications that were reviewed that discuss the topics of media sizing or wear, forty-five were studied in detail. These were grouped into: plant experiences; laboratory and pilot plant investigations; media wear studies; population balance modeling studies; and general papers on ball milling which included the topic of media sizing. The reader is encouraged to refer to that review. The findings remain unchanged, although some relevant papers have been written since (e.g. Staples et al, 1997; Banasi et al, 1999; Orford et al, 2006; LaMarsh, 2015). The main findings of the review were as follows."

Jan 1, 2018

By K. L. Boyd

"Can the ever-increasing tonnages of ore and waste being mined today be accommodated simply by using bigger and better crushers? This paper reviews the latest primary crushing and large cone crusher designs. It highlights how—in addition to using the larger crushers now available—maximizing the utilization percentages in each of the four stages of the rock size reduction circuit will assist in meeting the larger production requirements of existing and new mining operations. Its goal is to help consultants and operators select the optimal equipment and custom-designed items in the material handling flowsheet from the mine to the mill, maximizing operating hours per year. INTRODUCTION Are larger crushers the answer to meeting the demands of existing or new mining projects for increased tonnage? Boyd (2002) predicted that larger crushers for primary and fine crushing would be beneficial and contribute to the further development of mineral processing. Larger crushers for primary and fine crushing applications are now available. The rock size reduction process from the mine to the selected milling process facility has not changed since man first broke a rock to get at the interesting mineralization within. The rock size reduction process circuit from the mine to the mill can be summarized in four stages: • Stage 1: Mining (rock breakage and fragmentation) • Stage 2: Pre-screening (scalping) • Stage 3: Primary crushing • Stage 4: Fine crushing (secondary, tertiary and quaternary) Plant throughput and ore delivery schedule will form the basis for flowsheet design and equipment selection. Once the project design criteria and the mine plan have been established, the circuit’s utilization percentage (percentage of hours when the circuit is being utilized) can be optimized for each of the four stages. The mining and process departments are the key stakeholders in the selection of the final comminution circuit, and both departments should be familiar with and contribute to the design of the circuit. This paper focuses on the four stages of a rock size reduction circuit from the mine to the mill, equipment selection, various ore and waste handling flowsheets, and improvements in crusher station design, all with the purpose of maximizing availability and plant utilization percentages. What is a large tonnage? From 1907 to 1914, the American Panama Canal excavated 300 million tonnes of material in 7 years (History of the Panama Canal, Wikipedia). Today’s large mining operations can move the same material in 10 months, using large crushers or multiple crushers for ore processing and large crushers and a mixture of truck haulage and conveyors for handling the large waste tonnages. Some examples include:"

Jan 1, 2017

By P. M. Krishna

An example illustrates the use of ASTM Standard E901-82, Classification System for Uranium Resources. The example demonstrates the dynamic nature of the process of classification and attests to the necessity of addressing both the aggregate needs of broad-scale resource planning and the specific needs of individual property evaluation. Problems that ,remain in fixing the classification of a given uranium resource include the uncertainty in estimating the quantity of undiscovered resources and resolving the differences that may exist in deciding when the drill-hole spacing is adequate to determine the tonnage and grade of discovered resources.

Jan 1, 1983

By Y. M. Jiang

Many underground instabilities, such as excessive shield loading and roof falls, occur at longwall faces causing safety problems and production losses. Such instability problems are directly related to roof conditions which can be categorized using geological information. . However, most geologic information describing anomalies and variations of immediate and main roofs are not available before mining resulting in unexpected problems in a longwall face. It is apparent that the evaluation of these geologic anomalies provides a great benefit for longwall stability. The purpose of this study is to evaluate roof categories associated with geological anomalies employing fuzzy set theory. The evaluation is based on real-time monitoring information, such as shield leg pressure, developing load on shields, intervals of periodic weighting, and the ratio of developing loads during periodic to normal times. This paper introduces the application of fuzzy set theory for characterizing roof conditions and evaluating of roof similarities.

Jan 1, 1995

By Wei Li

Carbothermic reduction kinetics of ilmenite concentrates catalyzed by sodium chloride and the microwaveabsorbing characteristics of the resulting reductive products were investigated; the reduction degree of the reaction was deduced to be . Results show that the activation energy is 112.03 kJ/ mol when NaCl is used as catalyst, lowering to 23.11 kJ/mol for the final stage activation energy using sodium silicate as a catalyst. There is a sharp change in the reduction rate constant at temperature ranges of 1,223 K - 1,273 K and 1,373 K - 1,423 K. Microwave-absorbing characteristics of reductive products were measured by the method of microwave cavity perturbation. It was found that microwave-absorbing characteristics of reductive products obtained at temperatures of 850° C, 1,100° C and 1,150° C show sharp changes. Through X-ray diffraction (XRD) characterization, it was found that the formation of Fe occurs at a temperature of 900° C during the reduction process of ilmenite concentrate. The decrease of FeTiO3 content results in the decrease of microwave-absorbing characteristics, while the increase of Fe content gives rise to the increase of microwaveabsorbing characteristics. The decreasing trend is larger than the increasing trend, which is the main reason for the sharp changes in the microwave-absorbing characteristics of reductive products at the temperature range of 850° C to 900° C. When the decreasing trend is smaller than the increasing trend, it becomes the main reason for the sharp changes in microwave-absorbing characteristics of reductive products at the temperature range of 1,100° C to 1,150° C. Kinetics results show that sodium chloride can catalyze the carbothermic reduction of ilmenite, and microwave-absorbing characteristic investigations indicate that microwave heating can be used in the carbothermic reduction of ilmenite.

By Victor L. Steven

10.1-SHAFT SINKING AND RAISING BY CONVENTIONAL METHODS VICTOR L. STEVEN 10.1.1-SHAFT SELECTION A great deal of thought and planning should go into the selection of a mine shaft to provide the most effective use over the greatest, period of time. It sometimes is better to make an additional capital expenditure in the initial shaft program to achieve the greatest overall shaft usage. It is possible to sink a shaft which could be used for mine development, and initial production and later convert it to a ventilation, service or escape shaft. It is important to consider a second shaft in the original planning to provide ventilation, an escapeway and services for overall efficient production and safety. A second shaft usually is required to comply with state and federal mining laws. The main items to consider in shaft selection are: 1. Installation from surface or underground. 2. Vertical or inclined (sec Sec. 10.1.4L for discussion of factors involved in choice). 3. Tonnage to be hoisted. 4. Size of mining equipment to be lowered through the shaft to the underground workings. 5. Amount of water to be handled in the mining operation. 6. Ventilation requirements. 7. Type of ground the shaft is to be sunk through. 8. Position of shaft with relation to ore body. After the main features of a shaft arc determined, such as vertical or inclined, shape, size, type of lining and support, compartments, and shaft. facilities (air, water, ventilation, pump lines, power cahles, etc.), then :I sinking plant and procedures should be planned. At this point it should be decided whether the company will sink the shaft with its own crews or award the job to a competent shaft contractor. Company sinking generally will cost less if competent shaft men are available. Money also will be saved in plant costs, such as for hoist, headframe, compressed air, buildings, etc., as these will be part of the permanent plant and can be used in the sinking operation. Labor costs generally will be lower than contractor construction rates. The advantage of having a contract, or is the speed of completion of the project. Contractors usually have headframes and hoists ready to move on the job immediately and have trained crews ready to complete the project in the shortest possible time. Next, the type of surface sinking plant (hoist, headframe, etc.) should be selected and a determination made whether it is to be temporary or permanent. In most cases it is less expensive to install the permanent, headframe and hoist, and use them for sinking. The type of actual sinking equipment to be used should be evaluated for the most efficient sinking cycle, e.g., mucking method, drilling method, and lining or support means. The proper cycling of drilling, mucking and lining is extremely important in obtaining the most favourable sinking costs. 10.1.2 - GROUND STABILIZATION AND WATER CONTROL Prior to the shaft-sinking operation an investigation should be made into ground-water conditions. If water is anticipated, then pregrouting of the ground

Jan 1, 1973

By S. R. Rao, J. A. Finch, E. El-Ammouri, K. Ngoviky, P. A. Disten

Sludges produced by lime treatment of acid mine drainage (AMD) can contain significant quantities of base metals which represent both a potential hazard and a loss of values. A new technique for metal recovery from sludge is proposed by combining selective acid leaching and adsorption of metal ions by activated silica sol. The process is demonstrated on two AMD sludges, one containing primarily nickel and the second zinc. They were first treated with sulphuric acid (pH 3.5) to selectively leach the target metals and then activated silica sol was added to the leach solution to adsorb the nickel and zinc. Thickening and centrifuging gave about 90 percent rejection of the input volume to effluent. The adsorbed metals were redissolved by strong acid into a concentrated solution relative to the feed and the silica sol was recycled.

Jan 1, 2000