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By D. M. Stephens

Feeder-Breakers were an unknown but much needed piece of machinery when U. S. underground coal mines started converting to more efficient belt haulage of the R.O.M. coal as compared to conventional methods that the 1950's offered. These simple electromechanical machines offered efficiencies in three areas: (1) they contained a surge hopper that allowed a "load' of coal to be dumped without delay; (2) this material was fed horizontally by a drag chain conveyor into a rotating carbide pick breaker that broke all oversize material into a beltable size, and (3) it fed this broken material onto the belt conveyor at a rate conducive to its design. Since its introduction, the Feeder-Breaker has evolved from that first low capacity, low breaking force machine to today's model capable of breaking materials up to 5 MOHS in hardness and having throughput capabilities exceeding 3,000 TPH with availability in the 90 percentiles.

Jan 1, 1985

By L. Hagenbuch

Off-highway truck purchasers know the amount of tonnes, pounds, kilograms, etc, a truck will carry. However just because a truck is rated at 240 tons may in no way correlate to what that truck will actually carry. Two numbers define the carrying capacity of an off-highway truck: 1. The weight carrying capacity of the truck; 2. The volume carrying capacity of the truck. These two numbers must be in sync or the amount of payload carried will vary from the carrying capacity of the truck. Currently the Society of Automotive Engineers (SAE) standard J1363 January 1985 defines the volumetric carrying capacity of an off-highway truck. However as is well known in several South American countries, the SAE standard overrates the truck’s effective volumetric carrying capacity 15% to 20%. This paper presents a method for measuring “effective” body volumetric carrying capacity, resulting in a truck body for carrying the targeted load, matched to the loading equipment that interacts positively with the truck chassis.

Jan 1, 2002

By Stanley Bunk

The fluidized bed was invented by Fritz Winkler of Germany in 1921. The first application in the U.S. was in the development of the fluidized bed catalytic cracking of petroleum in 1942. Today, fluid bed cracking reactors are an integral part of every oil refinery. When fluid bed technology was first considered for applications outside the petroleum industry it was recognized to have uniform temperature, close control of the gaseous atmosphere and excellent mixing between solids and gases. Roasting of sulfide ores and concentrates was an obvious match. The first application was a single stage roaster for gold refining in 1947. There have been over four hundred commercial fluid bed roasters built and operated successfully in the four decades since the fluid bed was invented. There are three general categories of roasting applications. The largest number of roasters fall into the dead roasting category which includes gold ore roasters. The other categories are sulfating roasters and partial roasters (Reference 1).

Jan 1, 1990

By Nikhil Dhawan, Veeranjaneyulu Rayapudi, Singh Rahulkumar Sunil

The ever-increasing demand for steel and the subsequent depletion of high-grade ores requires the massive utilization of low-grade iron ores. In the present study, an iron ore slime sample containing 56.1% Fe was investigated using physical beneficiation, carbothermal reduction, and a microwave-assisted process; however, physical beneficiation and microwave exposure were found to be inefficient as they yielded lower iron recovery. Using coconut shell as an alternative reductant was found to be promising and does not lead to the formation of higher iron oxides, such as fayalite and wustite phases. The microwave-assisted carbothermal reduction was found at par with conventional reduction, saving time and heating. The optimum magnetic concentrate obtained in both carbothermal reduction routes (microwave and muffle furnace: Fe grade, Fe recovery, and yield of 64.3, 97, and 84%, and 67, 99, and 83%, respectively) are suitable for alternative iron-making or blast furnace units.

By K. N. Han, M. C. Fuerstenau, T. B. Onlin

A mathematical model describing the concentration profile of fine particles in the axial direction in liquid fluidized beds has been developed for the removal of fine particles. A forward finite differentiation technique has been used to solve a continuity equation with a source term to predict the concentration profile and, hence the recovery as a function of time. With the aid of experimental results obtained using a fluidized bed of 3-cm diam, dimensionless parameters were identified. These parameters were used to predict the concentration profile of fine particles in fluidized beds of larger sizes. Four different sizes of fluidized beds, namely, 1.3, 3.0, 4.0, and 7.5 cm in diam, were used in this investigation. The amounts of bed particles used included 4, 8, 16, 24, 59, and 120 g, and the size of bed particles were 48x100, 100x150 and 150x200 mesh.

Jan 1, 1987

By P. E. Snoek, R. L. Gandhi, C. S. Miller

Slurry operations are an integral part of mineral processing. There is therefore reason to consider using slurry pipelines for long distance mineral transportation. This paper reviews the current state-of-the art of such systems and, in particular, the design factors which must be addressed. It also discusses the selection of major components such as pipe, pumps, valves and storage facilities. Finally, the major steps required to determine the economic feasibility of a slurry system are listed and the major advantages and disadvantages of slurry pipelines compared with other forms of land transport are summarized. SLURRY PIPELINES: GENERAL OVERVIEW Minerals Transported Long distance slurry pipelines have been successfully used for transporting coal, iron concentrate, copper concentrate, limestone and phosphate. Additionally, several tailings disposal pipelines of considerable size and length have been built, but these generally are not categorized as long distance commercial mineral transportation systems. Table 1 lists selected examples of commercial slurry pipelines.

Jan 1, 1986

By O. Olajide, E. H. Cho

A laboratory study of the jigging process with Pittsburgh seam coal has been conducted. The laboratory-scale Baum jig used in this study was a McNally-Norton LO30X Right Hand Model Baum jig with an effective screen area of 0.186 m2 Feed material was prepared by selecting a size range from 6 mesh to 1.91 cm. Solid feed rates were 27.2 kg/min and 32.7 kg/min. Water flow rates were varied from 37.9 to 94.6 L/min. It has been found that smaller particles give higher values of density of separation and lower efficiency of separation. Increasing water flow rate increases the discharge rate of clean coal at a constant solid feed rate. It appears that the efficiency of separation increases by increasing water flow rate up to a certain value, and then levels off upon increasing the flow rate further.

Jan 1, 1988

By Robert Snow, Yingxue Yu, Patrick Zhang

The FIPR/SAPR process is FIPR's third approach to develop a viable alternative to the Crago "Double Float" process for phosphate flotation. SAPR stands for Single-collector, All-anionic Phosphate Recovery. The FIPR/SAPR process - offers a universal flowsheet for any anionic reagent system and flotation feed of varying sizes. For an unsized or fine flotation feed, the FIPR/SAPR process consists of the following steps: 1) high-solids conditioning with an anionic collector; 2) anionic rougher flotation, with the rougher concentrate sized at 48 (or 65) mesh and the +48 mesh recovered as a final product; and 3) cleaning flotation of the -48 mesh fraction from step 2. In a variation of step 2, the rougher concentrate from the first two cells may be collected as a final product, and the rougher concentrate from the last two cells sized at 48 or 65 mesh. The new process was tested with a blend of anionic collectors, achieving single-digit Insol at 85 + % recoveries.

Jan 1, 2002

By Ross W. Smith, Salim Akhtar

Flotation of oxide minerals, particularly silicates, with cationic collectors differs substantially from classic flotation of sulfide minerals using sulfhydryl collectors. In the case of cationic flotation of these minerals, in general: 1. There is a greater importance of electrostatic interaction between mineral and collector. 2. Longer-chained collectors are required; as a rule at least 10 carbons must be present in the hydrocarbon chain. 3. Moderate concentration of collector is required. 4. Attachment between collector and mineral appears to be less strong even though the system may exhibit a large contact angle. 5. Required conditioning time before flotation is usually relatively short. 6. There is sensitivity to slimes. 7. The collectors usually possess frothing power. 8. Selectivity of cationic collectors for specific minerals is usually poor. Almost any of the oxide and silicate minerals may be floated using cationic collectors. However, specific response to these collect- ors varies with mineral type. The following classes and minerals are

Jan 1, 1976

By Jim Truman

Appalachian coal mines include operations in eastern Kentucky, Maryland, Pennsylvania, Virginia and West Virginia. During 1994, they produced a total of about 342.5 Mt (377.6 million st) of bituminous coal. This figure represents 37% of the total production from the United States. This region contains nearly all of the nation's coking coal reserves and high-quality compliance steam coal that will be in demand after the turn of the century as utilities comply with phase two of the 1990 Clean Air Act Amendment. Figure 1 shows the location of the study area and the general regions that supply various coal types. Data for the study reviewed here were compiled and interpreted from Mine Safety and Health Administration (MSHA) production reports, Federal Energy Regulatory Commission 423 reports, King's Export database and additional data from the US Department of Energy's (DOE) Energy Information Administration (EIA). Table I is an overview of the total production from Appalachia and the delivered tonnage to various sales categories.

Jan 1, 1995

By Olli Järvinen

The precious metal refinery process is divided into the five process stages: 1 .copper/nickel leaching in autoclave 2. selenium roasting furnace 3. doré metal smelting furnace 4. silver electrolysis 5. gold recovery system. The process has been developed during the years in Outokumpu Harjavalta Metals, which treats about 600000 kg /year copper anode slime. The slime treatment process route in Outokumpu Pori plant has been developed from year 1941. During this period the process has been improved radically. The major changes has been the atmosphere leaching into the autoclave leaching, the sulfuric acid roasting furnace was changed into sulfuric dioxide / oxygen roasting. The old doré smelting furnace has changed into the TROF converter and the gold electrolysis / aqua regia process has changed into the quick hydrochloric acid leaching process. The current production in Pori plant is 30000 kg of silver, 1000 kg gold, 30000 kg of selenium and some hundred kg of platinum- palladium concentrate.

Jan 1, 1995

By Robert L. Cascio

The mining industry uses a large amount of electric power. Their equipment is subject to extreme environmental conditions and mechanical shock. A significant number of electrical accidents are a result of improperly grounded electrical equipment. Federal regulations require the safety ground bed resistance to be measured once a year or after modifications. Most commercially available instruments used to measure the ground bed resistance require the ground conductor to be disconnected and the power system disconnected for safety reasons. The "fall of potential1' method requires auxiliary ground rods and approximately two hours to complete the test. Although a new instrument was initially thought to measure the ground bed resistance immediately without isolating the ground bed, field tests have shown this method is not accurate. In some cases, a continuous measurement of the ground resistance is desired. A monitor has been developed and is presently being evaluated at several mines. These installations will be discussed.

Jan 1, 1992

In 1993, the United States' economy grew at a rate of about 3%. The Gross Domestic Product rose to $6.4 trillion. With more than 258 million people - 599,000 in mining including petroleum - the United States has more than 100 million dwelling units and more than 190 million licensed motor vehicles. New private housing starts rose 7% to 1.3 million units, new car production fell 3% to 5.5 million units and truck and bus production rose 21 % to 4.9 million units. The rate of inflation was under 3% and the prime rate of interest 6%. The Producer Price Index (1982 = 100) was unchanged from 1992 for fuels and re¬lated products and power at 80 and met¬als and metal products at 119, while chemicals and allied products rose 2% to 128 and non-metallic mineral prod¬ucts rose 2% to 120. The merchandise trade deficit rose 27% to $116 billion.

Jan 1, 1994

By P. R. Altringer, R. H. Lien, B. E. Dinsdale

The Bureau of Mines, U.S. Department of the Interior, is investigating biodegradation of cyanide as a means of decommissioning heap leach operations. Biological oxidation decreased weak acid dissociable (WAD) cyanide in process solutions from 50 to 170 ppm down to 0.1 ppm. The tests were conducted both in trickling column reactors, using quartz as the growth surface, and in upflow columns, using activated carbon as the growth surface. In addition, exploratory tests indicated that bacteria will destroy residual cyanide in leached ore. A flowsheet has been proposed for closure of heap leach operations in which the metals processing portion of the plant, possibly the carbon adsorption columns, or a collection pond is used as a bioreactor. The cyanide in the process solution is destroyed in the bioreactor and the treated water is used to rinse residual cyanide from the spent heaps. The water is recycled until the effluent WAD cyanide concentratio� meets discharge standards.

Jan 1, 1992

By Gary A. Perry

Cyprus Sierrita produces copper and molybdenum from its Sierrita and Twin Buttes open pit mines south of Tucson, AZ. Both pits were started in the late 1960s and are more than 460 m (1500 ft) deep. Sierrita has used a Caterpillar 992C Remote Controlled Loader since January 1993. The loader was justified to increase safety and profits at Sierrita. It has exceeded all expectations. As of June 1993, the 992C had produced additional profits of more than $1.5 million. Safety and Geotechnical The safety of Cyprus personnel and equipment is always of prime concern. The remote controlled loader removes personnel from the active raveling area. But it requires prudent operation. The remote controlled loader discussed here is always intended to be used in a safe manner under a managed slope. Any increase in slope angle or use of any equipment under a critical slope is taken only after careful analysis of the specific

Jan 1, 1994

By Kambhampati C. Rao, Cecil Lue-Hing, Nabih P. Kelada, William B. Willborn

improvements in the analytical techniques for cyanide speciation can furnish useful information about the behavior of the different cyanide species in the receiving environment. This could be of help to the environmentally concerned public and the regulatory agencies in the assessment of cyanide limits for effluents, stream quality, and land disposal of cyanide bearing wastes. In addition the ability to distinguish the free cyanide and the weakly bound cyanide from the strong ULTRAVIOLET IRRADIATION UNIT (LAMP, COIU3' HOUSING) FIGURE 1 complexes, as well as transformation to thiocyanate is also needed by different industries, such as mining and metal finishing, etc., to evaluate the efficiency of several processes. Cyanide has been used for the recovery of gold since the late 19th century. Although cyanide leach solutions are mostly recovered and used again, a large quantity of cyanide bearing wastewater becomes unfit for use and has to be treated before it can be released into natural waterways.

Jan 1, 1992

By Brendan Parker, Joseph Skrypniuk

Boddington Gold Mine1 (BGM) commenced production in 1987 and is currently ranked as the second largest gold producer in Australia. In a strategy to improve plant efficiency, constraints to plant performance were identified and prioritised with a view to maximising benefit for minimal expenditure. After identifying that leach kinetics and circuit residence time were major constraints, the introduction of oxygen was identified as having the greatest potential for the delivery of sig­nificant cost benefits. The application of oxygen, initially by conventional tech­niques, and subsequently by installation of Atomaer's Filblast gas shear reactor, improved gold recovery, reduced the resi­dence time constraint and enabled higher mill throughput to be achieved. Additional benefits included operation at lower pulp densities and a reduction in reagent usage. A significant reduc­tion in unit operating cost resulted from these benefits. This paper quantifies the above benefits in a format accept­able to both metallurgists and accountants by integrating the findings in a techno-economic perspective.

Jan 1, 1996

By P Simpson, P Bundo

The Eureka Mine is situated in the Guruve district of Zimbabwe, some 150 km north of Harare. The mine was first worked in 1895 and until recently was operated as a typical Zimbabwean "smallworking" with a single owner­operator and small labour force mining at up to 50m depth and processing 50 tonnes per day of ore via grind, gravity recovery and CIP. The gravity circuit comprised a Knelson 12" Centre discharge Concentrator from which a significant but variable portion of production was recovered. In 1996 exploration was commenced by Delta Gold Zimbabwe (Pvt) Ltd (DGZ), a wholly owned subsidiary of Delta Gold NL of Australia, with the aim of testing mineralisation and establishing a large-scale open pit operation. A feasibility study was completed in April 1998. Construction began in August 1998 and first gold was poured in June 1999. The mine is designed to produce 65 000 oz/annum of gold from 1.5 million tonnes of opencast ore grading 2 git Au.

Jan 1, 2000

By G. G. O. O. Uwadiale

Because mineral matter is finely distributed within the matrix, Nigerian Labia coal is nonresponsive to conventional processing techniques. However, testing has shown that Lafia coal can be upgraded by selective oil agglormation. The optimum oil concentration was found to be 10 mL of paraffin per 25 g of coal. A product containing 6% ash and 1.9% sulfur was obtained with a yield of 90%. Optimum results were achieved with a grinding; time of from 2.5 and 3 hrs, which produced a 98% -400 mesh product. However, further grinding wars found to be deleterious to the process. Also, high pH adversely affected concentrate yields. Utilizing kerosene as a bridging liquid, a product containing 4% ash and 0.33% sulfur was achieved at a natural pH of 6.3 with a yield of 85%. At pH 9 and 10, a product containing 4.5% ash was achieved with a yield of >90%.

Jan 1, 1997

By L. A. Arrington-Webb

Forty-four states produced clay products during 1994 for a total value of $1.6 billion. This was a 3% increase in total tonnage and a 7% increase in value from 1993. Kaolin Domestic production of kaolin during 1994 was estimated to be 9.3 Mt (10.2 million st), according to the US Bureau of Mines (USBM). Georgia remained the leading producer with 7.5 Mt (8.2 million st), followed by South Carolina with 535 kt (589,000 st). Kaolin used as a paper coating or filler pigment accounted for 51% of domestic consumption. Other uses included grogs (14%), fiberglass (5%) and plastics (4%). A reclassification by an Alabama producer of fire clay to kaolin accounts for the introduction of kaolin used in grogs. This also accounts for the apparent decrease in the use of kaolin in paper from 60% in 1993. However, the actual amount of kaolin used in paper was the same.

Jan 1, 1995