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By Gao Zhizhong, Zheng Shibo, Gu Zhengxing

Extensive research on the beneficiation of Florida dolomitic phosphate pebble has been carried out by Lianyungang Design and Research Institute of China (CLDRI) in recent years. Test results indicate that the fine-particle flotation process could be used to effectively recover the phosphate values from Florida high-dolomite phosphate resources. With the CLDRI fine-particle flotation technology, a phosphate concentrate with 31% P2O5 and less than 1% MgO could be obtained from a flotation feed containing 25.8% P2O2 and 2.2% MgO at an overall P2O5 recovery of up to 85%.

Jan 1, 1999

By C. A. Fleming, C. J. Ferron, I. Dymov

An oxidized gold/silver ore from Mexico has been evaluated at Lakefield Research in order to develop an economically viable treatment flowsheet for the recovery of gold and silver. Initial cyanidation test results indicated that at least 20 kg/t cyanide was required for maximum gold and silver extractions, due to high cyanide consumption by an oxidized zinc mineral present in the ore. A process was developed for the recovery and recirculation of the cyanide from the leach liquors. The proposed flowsheet included direct cyanidation, CCD and Merrill-Crowe, followed by precipitation of the zinc associated with cyanide with sodium sulphide and recycling of the regenerated cyanide liquor to the leach circuit. The process was demonstrated during a continuous pilot plant. A mill has been erected recently in Mexico and has been operating using this flowsheet.

Jan 1, 1997

By J. Hanna, I. Anazia

Selective fatty acid flotation of carbonate gangue from sedimentary apatites was achieved under acidic pHs without a specific apatite depressant and without conditioning the pulp with the collector. Concentrates (35% to 38% P2O5, 0.8% to 1% MgO) with high recoveries (80% to 85%) were produced from Indian and Chinese dolomitic ores. The calcareous and/or dolomitic-siliceous phosphate ores of South Florida and Utah required two flotation stages: one for carbonate removal, as mentioned above, and the other for phosphate recovery from siliceous gangue. Preliminary tests on the South Florida ore gave concentrates analyzing 29% P2O5 and 0.8% MgO, with a P2O5 recovery of 76%. A concentrate obtained from the western US phosphate ore from Utah assayed 30% P2O5 and about 1% MgO, with a P2O5 recovery of 89%.

Jan 1, 1988

By B. Govindarajan, L. S. Rao, T. C. Rao, B. R. Rao

Laboratory leaching experiments were conducted to extract potassium from glauconitic sandstone, and the effects of important variables were studied. The reduced time plot (RTP) for all of the variables obtained from the experimental data has been quantified by this simple equation: R = 100 (1 - exp (-0.693 *(T/T50)0.605) The time required for 50% extraction (T50) has been correlated by a regression equation to variables such as acid strength, temperature, fluorite: glauconite ratio and % solids. Both of these equations were used to predict the extraction percentage at different process-variable levels. In addition, several other experiments were conducted at arbitrary levels of the variables to verify the equations developed.

Jan 1, 1994

By C. L. Karr

Researchers at the University of Alabama have developed a method for producing fuzzy linguistic models of mineral processing equipment directly from engineering data. These fuzzy linguistic models rely exclusively on data collected from the processing systems being modeled and do not presuppose an understanding of the physics of the system. The fuzzy linguistic models use descriptive rules and explicit membership functions that provide a precise, nonmathematical description of the processing equipment. A genetic algorithm is employed to simultaneously select rules and tune membership functions used in the fuzzy models. The result is an extremely flexible approach to modelling that is applicable in a variety of linear and nonlinear systems. The effectiveness of this approach to modelling is demonstrated using a four-input, two-output model of a grinding circuit.

Jan 1, 1996

By R. M. Quinlan

The coal industry in the United States has undergone significant economic changes during the past six years. The price of coal remained relatively constant from 1950 to 1969 (See Figures 1 and 2). Steam coal prices tripled and metallurgical coal prices doubled from 1969 to 1974. This price structure has created a new economic environment for coal preparation. Contributing factors to these price trends include: ? Coal Mine Health and Safety Act of 1969 ? Mid-East oil embargo of 1973 ? United Mine Workers of America contract agreements ? Productivity decrease (tons per man-day basis) ? Environmental Protection Agency regulations The increased value of coal justifies additional capital investment in cleaning facilities to optimize yield. Current trends include recovery of existing slurry ponds and recleaning of refuse. Coal preparation plant product yield and quality must be evaluated in terms of the amount of capital expended and cost of operation. Therefore, it is advantageous to optimize the plant product based on clean coal selling price and rate of return on investment.

Jan 1, 1976

By Khaled Morsy

Cementitious seals are made of foamed cements with strength ranging from 100 to 600 psi. These cementitious seals are usually used at locations where the seal will be subjected to some convergence, assuming that this material can absorb entry closure without compromising the structural integrity of the seal. Prior to 2006, Lake Lynn Experimental Mine (LLEM) conducted full-scale tests on various cementitious seals designed to meet or exceed the 20-psi horizontal static load requirements of the old 30 CFR1 75.335. Both hydrostatic and dynamic loading tests were conducted. The structural response (pressure and displacement readings) obtained from these tests were recorded. The stability of the cementitious seal is based on balancing the load applied to the face of the seal from the explosion against the shearing resistance at the seal/rock interface. Therefore, the properties of the seal/rock interface, such as stiffness, cohesion, friction, etc. are critical to determine the stability of a cementitious seal. These properties are usually assumed by the researchers in their models. This paper emphasizes the importance of having the correct properties of seal/rock interface in the numerical modeling. FLAC 3D models were developed to simulate Celuseal2 cementitious seals subjected to both hydrostatic and dynamic loadings. Using the hydrostatic and dynamic loading test data conducted at LLEM, the static and dynamic properties of the seal/rock interface were back calculated. The FLAC 3D models showed good agreement with the test results.

Jan 1, 2009

By F. F. Aplan

The material known as coal has a highly variable composition. As a consequence, coals show a great variation in their physical and chemical properties as a function of coal rank. The situation is further complicated because the preparation engineer must deal with raw coal, as mined. This is an assemblage of coal, upwards of 30% mineral matter and, typically, several percent pyrite. The kind and amount of the mineral constituents is also highly variable from source to source. A knowledge of coal rank and source location, and the kind and amount of associated impurities, is the first step in evaluating the response of a raw coal to preparation procedures. The raw coal must first be characterized before information from one source can be extrapolated to that of another.

Jan 1, 1988

By George S. Koch

Today, after about 30 years of development, computer-based analysis of geoscience data has reached a mature phase. From the tentative early beginnings recorded in the proceedings of the APCOM meetings, geoscientists are now able to emphasize the need for both pertinent mathematical/statistical models and computer hardware and software. From those models that are well understood in the disciplines of statistics and mathematics and for which effective computational methods are available, practitioners select and develop methodology for their particular purposes. Computer hardware is typically assembled from off-the- shelf components now readily available, with particular emphasis, whenever feasible, on microcomputers for reasons of economy and control by the scientific or engineering user rather than by a bureaucratic computer center. Computer software may be written by the user in high level languages such as Pascal, FORTRAN, or LISP. However, more often today geoscientists use routines available in spreadsheets, data bases, or statistical packages. In so doing, they save time and, programming costs and take advantage of routines written and maintained by large, well- established organizations, while losing the flexibility in specifying exact input/output afforded by writing in a high level language.

Jan 1, 1989

By David Jenkins

Grefco Inc. operates two diatomite mines in the western Santa Ynez Mountains. The larger of the two mines, the Palos Colorados Mine, is located approximately seven miles southeast of Lompoc. The Miguelito Mine is located about two miles south of Lompoc on the west side of the Miguelito Canyon. Diatomite from the Palos Colorados and Miguelito mines is trucked to the Grefco plant at Lompoc for processing (Figure 1). HISTORY Grefco, Inc. evolved from the originating Dicalite Company which in 1929 began operations at the Walteria plant in the Palos Verdes Hills south of Los Angeles. In 1942 Dicalite leased the Palos Colorados mine at Lompoc. In 1944 the Dicalite Company was purchased by Great Lakes Carbon Corporation.

Jan 1, 1995

By E. Lefeuvre

Precambien in age, the phospate deposit under study which outcrops to the south forms a synclinal consisting of only one mineralized horizon. The synclinal strikes SSW/NNE, dips from 30 to 60 NNE and is about 5 km wide. The deposit has been explored by : - trenches and pits about 50 m apart in the outcropping area ; - core drill holes forming lines perpendicular to the outcrop. These lines are about 100 m apart. On each line, the drill holes are about 50 m apart The phosphate layer is clearly visible and has then been defined from the geologicia1 description of drill hole logs. The layer has been divided into two parts : a very rich, altered part at the hanging wall and a poor part displaying opposite physical characteristics, i.e. a fresh and hard rock. With open pit mining in view, the deposit has been divided into a 3-dimension network of blocks, each block measuring 50 X 50 X 100 m. The tonnages of rich and poor ore, PO25, MgO, Si02, CaO and R2O3 grades and the tonnages of barren waste at the hanging wall and the footwall have been calculated for each block. Given the dip of the phosphate layer ranging from 30 to 60° and its relative thickness (between 10 and 15 m), it was impossible or inappropriate to carry out direct calculation by 3-dimension kriging : too many neighboring blocks to obtain sufficient date and impossibility to draw up the morphology of the layer.

Jan 1, 1986

By G. T. Adel

Hindered-bed separators are often used in the minerals processing industry to classify particles according to size and density. A new technology, known as the CrossFlow, was recently developed to overcome some of the limitations associated with hydraulic separators. The innovative feature of this unit is a novel feed presentation system that improves separation efficiency and capacity. In the present work, a detailed process engineering evaluation was conducted to determine the basis for the improved performance of this unit. The evaluation included controlled separation tests using well-characterized feeds, particle and liquid tracer experiments, and mathematical modeling studies. Data obtained from this work show that the new separator is capable of maintaining good separation efficiencies at higher solid feed rates than traditional designs due to improved hydrodynamics in the separation zone. This paper reviews the operating principle of the CrossFlow separator, discusses the results of the tracer experiments and modeling studies, and presents test data obtained from recent laboratory and plant trials.

Jan 1, 2001

By G. Roy, C. B. Pettersson, S. Nandagiri, D. J. Ivor-Smith

The Coastal Water Authority's 2,740mm/2,590mm (108 in./102 in.) pipeline, known as the Northwest Lateral Project, will transport raw water from an existing pipeline over 14.3 km (8.9 miles) to the City of Houston's East Water Purification Plant. The new pipeline crosses under Houston Ship Channel and Greens Bayou in tunnels at approximately 30.5m (100 feet) and 25.9m (85 feet) depths, which present unique experiences in tunneling under open bodies of water in the Gulf Coast's soft ground conditions. An earth pressure balance TBM is being used for the deep tunnel sections where the ground demonstrates high overload factors and variable conditions ranging from clays to silty sands. This paper discusses the design approach for the tunnels and shafts, ground conditions, constructability, and selection of the primary lining system.

Jan 1, 1989

By Thomas H. Wake, Timothy M. Tower

A continuing trend in raise drilling is the movement toward increased automation. This paper discusses the reasons for automating a raise drill, which include labor saving, faster and smoother operation, quicker response to blocky ground, and improved data logging and diagnostics. It gives a "wish list" of features when automating a raise drill, from simple shutdown control through unattended operation. It discusses the principles involved in closed loop control of a sluggish mining machine with large inertia, and covers functions such as data logging and remote control. Results are presented from a field test on a production raise drill.

Jan 1, 1991

By F. L. Pirkle, D. A. Podmeyer

The mineral zircon is mined for use as specialty foundry sands, abrasives, ores of Zr02 and zirco¬nium metal, refractories and zirconium chemicals. It is produced as one of several products from heavy-mineral sand deposits associated with ancient shorelines. Because of its low coefficient of thermal expansion, its high melting point, its high refractive index and its chemical inertness, it is an attractive refractory material. Zircon varies from deposit to deposit in terms of grain size, grain shape and chemical purity. Thus, there is a wide range of commercial zircon products that differ in impurity levels, particle shapes and grain sizes.

Jan 1, 1993

By Menzhans Guo

A coal bunker basically acts as a buffer and regulator to reduce the interruptions between its proceeding production system and succeeding haulage system so as to maximize the availability of the whole system. Although such a role has long been recognized, quantitatively studying it is still rarely seen in the literatures. Its unique characteristics, coupled with numerous transitional states, make it very complex to describe the state transitional process in analytical models and, also very difficult to seek an analytical solution. Moreover, the analytical models inappropriately consider the state of bunker being full or empty as a kind of failure, therefore, by no means can they realistically describe the impact of the difference between rates of coal flowing to and from a bunker on the system availability. In light of this, Monte Carlo simulation methods are suggested to reach an approximate solution. In comparison, simulation methods are simpler and more effective than analytical approaches. Applications of simulation methods to a Northern colliery for determining bunker size from the viewpoint of maximizing system's availability are discussed. The results are satisfactory.

Jan 1, 1992

By A. A. Schweizer

This paper documents the growth and projects the future of Green Diamond Sand Products. Since1954, Green Diamond, located in Riddle, Oregon, has been producing sand from granulated nickel slag for use in various markets. Through the years, the company has seen several changes from its ownership to its product lines. In 1991, Green Diamond was producing abrasive sand at a rate of about 30,000 tons per year. It was at this time that Green Diamond became part of Glenbrook Nickel Company. Over the next eight years, Green Diamond would quadruple its production to over 140,000 tons while moving into three new markets, as well. Green Diamond is now producing sand for use in the abrasive, foundry, construction, and roofing industries. In 1998, Green Diamond again found itself under new, private ownership. With plans on developing agricultural sand and spent abrasives recycling, the future of Green Diamond appears to be one of further expansion coupled with diversification of its product lines.

Jan 1, 2000

The market for titanium feedstocks (ilmenite, rutile,synthetic rutile and slag) is driven primarily by offtake from the titanium dioxide (TiO2) pigment industry. The pigment sector depends on the performance of the global economy. Titanium sponge is the first stage of titanium metal manufacture. It constitutes a minor component (3 percent) of overall demand for titanium feed-stocks. Production and consumption TiO2 pigment consumption in 2004 was estimated to be 4.63 Mt (5.1 million st), up 7.6 percent from 2003. It was driven by strong demand in most regions. In the United States, apparent TiO2 pigment consumption rebounded by 5.4 percent (highest growth rate since 1997) to an estimated 1.12 Mt (1.23 million st), following the decrease in demand during 2003. Chinese TiO2 pigment consumption continued its strong upward trend, increasing by 10 percent to 598 kt (659,000 st) in 2004.

Jan 1, 2005

By Paul Mitchell, Amy Wheaton, James Rybock

Acid rock drainage (ARD) represents one of the most intractable problems faced by the non-ferrous metal and coal mining sectors, and the creation in the recent past of a number of high-level national and international initiatives reflects the growing concerns of industry, government and other stakeholder groups. ARD is certainly considered one of the most serious environmental impacts caused by mining and the industry's greatest environment-related technical challenge. Additionally, the global depletion of non-acid generating oxide ore deposits and the increasing dominance of sulphide ores means that the potential for ARD incidents will continue to increase. Once initiated, the cycle of chemically and biologically mediated and catalysed reactions leading to ARD generation is difficult to stop. While there is evidence to suggest that the degree of contamination of ARD will decrease rapidly within a relatively short timeframe (Wood et al., 1999), experience in historic mining regions of the world indicates that the problem may persist for centuries at certain sites. Current best practice in dealing with ARD puts the emphasis on prediction and prevention, planned from the outset of the operation and integrated with each phase of the mine site life cycle. The elements that constitute best practice are becoming more clearly defined and as this process of clarification continues industry will undoubtedly accelerate the process of best practice implementation, burying at last the image of mining as a despoiler and polluter of landscapes, an image based on past, rather than current, practices. However, it is equally clear that despite the best efforts of industry and regulators, many sites will continue to generate ARD during operation and following closure - in many cases, a legacy of ARD has been derived from operational and strategic decisions made decades ago, before the risks and impacts of the self-sustaining cycle of ARD generation were properly understood. Add to this ARD generation from poorly managed operations and from historic and abandoned sites, and it becomes clear that the treatment of ARD will be required for the foreseeable future to protect water quality, and ecosystem and human health.

Jan 1, 1999

By S. K. Kawatra, R. A. Seitz

There is considerable variation in the types of coal flotation circuits in use in various parts of the world. For example, Russian plants frequently use scavenger flotation, while this is almost unheard of in the United States. The numerous circuit designs are intended to address specific problems in coal flotation, or to take advantage of the peculiarities of certain coal deposits. As a result, it can be difficult to decide which circuit is best for a given application. For this paper, coal flotation circuits were collected worldwide from many operating plants. These circuits include varying degrees of conditioning, and complexity ranging from simple rougher flotation to multi-stage split- stream processing. The design goals of each circuit are described, and the advantages and disadvantages of each are discussed. Extensive sampling campaigns were carried out in two plants with the most common types of coal flotation circuit (simple rougher, and rougher with deslimed feed). The performance of each plant was evaluated, and the benefits of more sophisticated processing in each case are described.

Jan 1, 1993