Search Documents

By Benjamin C. B. Hsieh

Many processes in the hydrometallurgical and chemical industries require the separation of dissolved material from suspended solids. Counter current decantation (CCD) with thickeners is one of the methods generally used. The process engineer needs a quick and accurate CCD calculation method. Several theoretical 1-12 CCD calculation methods are available in the literature . The simultaneous 1, 2 equation method for a complex circuit as used would take too long to solve the problems. Approximate equation method1 is not accurate and is for simple cases only. A shortcut method developed by Counselman3 contains no mathematical equation, and thus is not suitable for computer programming. Based on Counselman's method, Woody4 derived two simple equations in terms of percent soluble loss for two typical examples. Scandrett5 included a term for mixing in his formulas. This mixing efficiency was defined by Murphree6. Another method which depends on making volume calculations instead of using weights is presented by Mastin8 and Cahalan9. None of these methods is related to dissolution and pre¬cipitation reactions. Chen 10,11 demonstrated his methods for counter current leaching. His results are calculated from the general solution of a derived linear difference equation for constant underflow, and from the solution of a derived non-linear Ricatti difference equation for variable underflow. This paper concerns derivation of a general equation for CCD washing with provisions for adding and withdrawing the streams, and for leaching (dissolution) or precipitation reactions. These equations take several forms depending on the input information available. A set of simplified equations for continuous counter current washing and leaching is derived for determining:

Jan 1, 1972

By Gunter Fauth

The setting of tasks for the process control of coal cleaning, and in this connection the requirements for instrumentation can be classified into the following three fields: - Monitoring the operation of individual units, or process steps, - Control of units or process steps, - Control of the entire coal cleaning process with the intention of optimizing the operation and the profitability of the process. Instrumentation is affected by the type of cleaning processes. For introduction Figure 1 shows the simplified flow sheet of coal preparation which is usual in the German Ruhr District and in which desirable places for the measurement of ash, moisture and sulfur content are marked. The preparation plant is supplied with run-of-mine coal from the shaft via a homogenization facility. In a first step of primary classifying the raw feed coal is screened at about 10 mm. The raw coarse coal ( = 10 mm) is sorted by jig washers or heavy-medium separators. the raw fine coal (< 10 mm) at first is pneumatically sized at about 0.5 to 0.75 mm. The fines, the aspirated dust, are a finished partial product which will be added to the final metallurgical or steam coal. The material 10 to 0.75 mm subsequently is sorted in fine coal jigs and dewatered in centrifuges. The sludge obtained with the wet cleaning processes is dewatered in thickeners and fed to the flotation. Concentrate and tailings are dewatered by filters or bowl centrifuges and by chamber filter presses or belt filter presses, respectively. The partial products coarse coal, fine coal, flotation concentrate, aspirated dust, and middlings are blended to result in the sellable products metallurgical and steam coal.

Jan 1, 1984

By Frank W. Schmechel

The subsidence monitoring program at the Old Ben No. 24 Mine was planned in 1976 as part of the on- going demonstration of longwall mining. The construction and installation of the network of surface subsidence monuments was started in Play of 1976 and completed four weeks later after which an initial reference survey was made of all surface monuments. Mining of the first longwall panel started in September of 1976 and was completed in May of 1977. Mining of the second panel started in August of 1977 and is continuing at this time. The Automatic Data Acquisition System (ADAS), which is the subject of this paper, was installed over the second panel on March 29, 1978 near the panel center (Figure 1) and approximately 104 meters (370 feet) in front of the face position at that time. Mine No. 24 is located approximately 5 kilometers (3 miles) Northwest of Benton, Franklin County, Illinois. Coal is being mined from the Illinois (Herrin) No. 6 seam which is at a depth of about 189 meters (620 feet) at the site. The Herrin No. 6 is up to 2.7 meters (9 feet) thick in the mine but a constant thickness of 2.1 meters (7 feet) is being mined by the demonstration longwall with both roof and floor coal being left for stability. Although the seam is flat laying at the mine, it dips north- ward regionally. Topographically, the surface over the demonstration panels is essentially flat and low laying with several areas of standing water. The Rend Lake Dam (United States Army Corps of Engineers) is about 305 meters (1000 feet) north of the demonstration site.

Jan 1, 1979

By N. B. Aughenbaugh

A study was made to determine those petrographic parameters that are correlative with carbonate-aggregate quality as indicated by the Los Angeles abrasion and absorption tests. Samples collected at 28 sites in northern and eastern Indiana were analyzed petrographically, chiefly for void content, grain size, grain-size variation, grain shape, and grain interlock. Most of the sampled sites are in the belt of Silurian rocks of east-central and north- western Indiana. Though a few sites lie outside this belt, most of these have only a thin Devonian section above the Silurian. Three sites are non-Silurian and are included for comparison. Most of the samples studied are from Middle and Upper Silurian units. Both biohermal and nonbiohermal facies are included. The biohermal rocks are typically dense but vugular, finely crystalline granular dolomite. Nonbiohermal facies are porous, medium to coarsely crystalline, granular dolomite with dolomite rhombs The Los Angeles abrasion losses ranged from 20 to 46 per cent, the rocks in the eastern part of the state showing the higher values. Absorption tests indicate the same general quality trend. Comparison of petrographic studies with Los Angeles abrasion- and absorption-test results indicate the following correlations. (1) As per, cent of voids increases, quality decreases. (2) As average grain size increases, quality decreases. (3) Variations from mean grain size appear to have no effect on the quality. (4) As angularity and roughness of the grains increase, quality increases. (5) As grain-to-grain interlock increases, quality increases. Variations in the calcium-magnesium ratio have no apparent effect on aggregate quality, except as they affect the texture.

Jan 1, 1966

By Basar Arioglu, Jaeung Kim, Mehmet Öztürk, Jinmoo Lee, Dongho Lee, Taek-Kon Kim

"Istanbul Strait Road Tube Crossing Project (Eurasia Tunnel) includes 3.34 km of a bored double-deck tunnel under the Bosphorus Strait, at a maximum depth of 106 m from the sea level, and 1 km of twin NATM tunnels on the Asian side. The region’s variable geology, hydrology and propensity for seismic activity, combined with high water pressure and large-diameter/double-deck tunnel configuration, make the Eurasia Tunnel one of today’s most challenging and complex projects under construction. Due to the site’s proximity to the active North Anatolian Fault, the tunnel is designed to withstand a 7.5 magnitude earthquake. The tunnel penetrates through both the Trakya bedrock (on both European and Asian sides) and the alluvial sediments at the bottom of the channel. The tunnel is designed to accommodate differential displacements by introducing seismic/flexible joints at proper locations at the transition zones between rock and soft soils. Tunnel fire is also a significant design consideration for undersea tunnel due to that the rubber protecting it in close proximity of the seismic joint should resist a fire for long term safety and durability. This paper mainly focuses on the design for method of tunnel response analysis in transverse and longitudinal direction against seismic demands relating with the seismic joints. INTRODUCTION Istanbul Strait Road Tube Crossing Project (Eurasia Tunnel) will build and operate a roadway tunnel under the Borphorus connecting Kazlicesme on the European side and Goztepe on the Asian side, to provide additional road-access across the Strait and consist of three main parts as shown in Figure 1."

Jan 1, 2016

By Ross A. Scarano

It wasn&apos;t until late 1976 that the U. S. Nuclear Regulatory Commission (NRC) set about to address the uranium tailings issue in earnest. It was decided that a generic environmental impact statement related to uranium milling operations would be prepared to support formal tailings regulation. We recognized, however, that this was a task that would take many years to complete and we could not take a "business as usual" approach to tailings management in the interim; the issue was too sensitive. To facilitate licensing during the interim period, the NRC developed guidelines in May 1977, for the industry in the form of the following performance objectives for tailings management: Siting and Design 1. Locate the tailings isolation area remote from people such that population exposures would be reduced to the maximum extent reasonably achievable. 2. Locate the tailings isolation area such that disruption and dispersion by natural forces is eliminated or reduced to the maximum extent reasonably achievable. 3. Design the isolation area such that seepage of toxic materials into the groundwater system would be eliminated or reduced to the maximum extent reasonably achievable. During Operations 4. Eliminate the blowing of tailings to unrestricted areas during normal operating conditions. Post Reclamation 5. Reduce direct gamma radiation from the impoundment area to essentially background. 6. Reduce the radon emanation rate from the impoundment area to about twice the emanation rate in the surrounding environs. 7. Eliminate the need for an ongoing monitoring and maintenance program following successful reclamation plan. 8. Provide surety arrangements to assure that sufficient funds are available to complete the full reclamation plan.

Jan 1, 1980

By Norman K. Olson

Hard-rock phosphate was formerly the chief source of all phosphate in Florida. Its mining began as early as 1883 or 1884, reached a peak level in 1907 and ceased in 1966. Production began and ended in the Dunnellon area (Marion County). Nearly all the hard-rock was exported because its P205 value per unit weight is generally more concentrated than that of other phosphate rock. Maximum production, achieved in 1907, was greater than 600,000 tons; the total value for that year was more than $4,000,000. The Florida hard-rock phosphate, considered to be of middle Miocene to early Pliocene age, has an intermittent narrow, linear northwest-southeast trend. The Ocala uplift controls the phosphate distribution for more than 200 miles. Other known, isolated hard-rock areas appear to be related to minor folds on the Ocala uplift. The hard-rock phosphate deposits are a heterogeneous mass of sedimentary fluorapatite, chert and quartz with textures ranging in size from clay to boulder, and in thickness from 0 to 40 feet. Phosphate compounds, principally fertilizers, have been in oversupply since before 1968, but by the middle 1970&apos;s some experts forecast a supply-demand balance. A brighter future for exploitation of Florida hard-rock phosphate depends upon one or more of these factors: 1) depletion of present premium grades (74 percent BPL and above) of land-pebble; 2) cheaper electric power from nuclear generators for profitable electric furnace operation; 3) supply and price of sulfur; 4) manageable rail-water transportation costs; 5) development of less costly mining and separation methods; and 6) minimum competition from high-grade foreign phosphate.

Jan 1, 1972

By Ted C. Mathews

Pre-concentration by sorting is as old as the mining industry. Inevitably waste rock is broken with ore. Separation may take place in the stopes by selective mucking and transport, or selective loading and transport of ore and waste by 12-cu, yd. shovels and 100-ton trucks in large open pit operations. Hand sorting of 1" to 16" pieces, formerly widely practiced at underground chutes and prior to or following first stage crushing, has greatly diminished in the United States with its high per hour labor cost, although still widely practiced in other countries and, surprisingly, in some of the most modern mills where inexpensive labor is available. The economics of pre-concentration by sorting is attractive since elimination of waste at any cost less than the total milling cost will show a profit. The size at which sorting should be under- taken is determined by the size at which liberation is secured to yield a product of ore and waste, and greatly influences cost and the point in the flowsheet where sorting can be undertaken. In some instances mining costs can be reduced where an inexpensive sorting system to eliminate waste is combined with a less selective and less costly mining method. This is particularly true in deep mines where hoisting capacity determines the rate of extraction and sorting is performed underground, with waste utilized for fill. Hand sorting, while efficient, is expensive because of low sorting rates. Peale (1) quotes man hour capacity at 1/3 ton per hour on sizes 3/4" to 3" copper ore, and up to 5 tons per hour on rich iron ore sized from 4" to 16".

Jan 1, 1974

The Bagdad mill, built in 1977, was de-signed for a mill capacity of 36,300 tpd. An ABC (Autogenous Mill-Ball Mill-Crusher) grinding circuit was chosen. The original mill contained three completely independent grinding circuits, each containing one 9.75 m diameter by 3.96 m long fixed speed autogenous mill, one 4.72 m diameter by 6.71 m long ball mill and one 2.13 m diameter short-head cone crusher. Total installed power per grinding circuit was 8,464 kw with 5,966 kw in the autogenous mill, 2,237 kw in the ball mill and 261 kw in the crusher. (See FIGURE I--Major Equipment Flow Diagram.) The autogenous mills were designed to be able to operate semi-autogenously but were never converted to SAG. As a result of this design, only about 4,100 kw of the designed power is utilized in the autogenous mills. The grinding circuits are closed with 2.44 m by 6.10 m double deck vibrating screens. Screen oversize is returned, by a series of conveyors, underneath the mill coarse ore stockpile to feed the crushers. Variable speed belts feed the crushers and control power draw. Crusher product reports directly to the tail end of the autogenous mill feed belt. (See FIGURE 2--Typical Crusher Feed and Product Size Distributions.) Tramp iron in the autogenous mill-crusher circuit is handled in a unique way. A magnetic sensor detects the metal. This closes a gate which directs the crusher feed onto a separate belt which bypasses the crusher and returns the material to the autogenous mill feed belt.

Jan 1, 1992

By Pierre Dosmond

In ore mining technology, the loading and hauling operations are undoubtedly the area where the most spectacular progress has been made during the last twenty years. I shall draw some examples from the Eastern France iron ore mines which I how well and whose production of 62 million tons for 1962 and 1963 constitute a worthwhile experience worldwide. The iron ore deposits of Lorraine are of sedimentary origin. They contain many mineralized horizons with workable seams situated from 330 to 830 ft. in depth. The dip of these seams is generally less than six percent. Their thickness varies from 6 to 23 ft. All seams are not workable throughout the whole area of occurrence, but in some mines there are five mineable seams in the same vertical section, with from 5 to 20 ft. of barren ground intervening between them. The iron content of the mineral varies from 28 to 36 percent. Specific gravity of the ore is 156 lb. per cu. ft. m place and 100 lb. per cu. ft. blasted. Reserves of iron ore in the Lorraine region are estimated at six billion tons with an iron content of more than 28 percent. These mines operate by means of rooms and pillars process, with pillar robbing; the final recovery is very good and averages 90 percent. Some years back, competition from richer, imported ores incited these mines to make constant efforts to increase their productivity and reduce mining costs, thus placing them in a leading position in mining technology, as evidenced by the dramatic evolution of their output per manshift (Figure No. 1).

Jan 1, 1970

By Kim A. Lapakko, William W. III White

The ASTM standard method D 5744-96 was developed to provide a well-defined kinetic test protocol, conducted under controlled reaction conditions, with the intent of generating reproducible results. A preliminary indication of the repeatability of a simplified alternative method (MN DNR method) was assessed and results from the MN DNR method were compared to those from the ASTM method. To provide an indication of repeatability, six samples from three different rock types were subjected to dissolution testing for periods of 20 to 68 weeks. Drainage pH values at the end of the tests were within 0.5 units in all cases and within 0.05 units in four cases. The percent difference from the mean for overall sulfate rates from paired cells ranged from 0.04 to 1756, with a median of 6.3%. Nine samples from four rock types were subjected to both MN DNR and ASTM tests for periods of 20 to 132 weeks. The difference in final drainage pH values forsix of the samples was less than 0.1 unit, and these values were less than pH 3.65 or greater than pH 8.0. The final drainage pH difference for the last three samples ranged from 0.15 to 0.4, and these values were ill the pH range of 6.2 to 7.2. The sulfate release rates for the periods of record for the MN DNR method were 70 to 150% of those for the ASTM method, with a median value of 110%. Sulfate and calcium release from the two methods was not substantially different. The MN DNR method typically produced higher magnesium release.

Jan 1, 2000

By David A. Holmes

After a century of variable government-supplied housing on their cold, windswept lands, and facing extremely limited natural resources and no timber, the Standing Rock Sioux Tribe has launched a study into alternative housing approaches for their people. Considering that they have little more than the soil and limited river aggregates under their feet, the Tribe has elected to consider adobe and earthen-wall construction. Earthen construction is no stranger to the Sioux lands. Smaller tribes, including the Mandan, Arikira, and Hidatsa, lived here among the Sioux in earthlodges for centuries. Such earthlodge structures were not unlike the Southwestern jacal style-a framework of upright branches and branches covered with mud-employed by the Anasazi about A.D. 700-900. Indeed, the Sioux people themselves evolved from earlier earthlodge dwellers. Indigenous peoples in New Mexico, Arizona, and neighboring Mexico have used earthen-wall housing for many centuries, reinforcing Sioux observations that this is today an earth-friendly, cost-effective, and practical approach. The Cheyenne River and Pine Ridge Sioux Reservations also recently have conducted studies on earthen- wall construction. This paper describes the search for and evaluation of potential raw-material resources for earthen-wall/adobe construction on the Standing Rock Reservation in North and South Dakota. Significant resources of clay/silt materials (8 million tons in the Striped Cloud clay bed) suitable as adobe binders and sand-and-gravel aggregate (2.5 million tons) that could support earthen/adobe construction have been identified throughout the Fort Yates Flat area on the Reservation. Also addressed is how adobe and rammed-earth construction could add to the diversity of reservation construction and address future Tribal housing and other building needs.

Jan 1, 1999

By Brett P. Spigarelli

To meet the growing need for CO2 capture and storage technology, Michigan Technological University is researching CO2 capture and storage using alkali solutions1. Without implementing emission controls, world energy emissions will rise from 29.7 billion t in 2007 to 42.4 billion t in 2035. The first objective of the project was to determine the optimal amount of alkali in solution for CO2 absorption. This was accomplished using theoretical equilibrium calculations and experimental absorption data for alkali solutions of 1, 2, 3, 4 and 5 weight %. As the % alkali in solution increased, so, too, did the ionic strength of the solution. Theoretical calculations took into account the effect increasing ionic strength will have on the solubility of gaseous CO2. The calculations assumed negligible formation of H2CO3, constant temperature and constant pressure. In the experimental setup, a 16% CO2 /balance air gas mixture was bubbled through an Erlenmeyer flask filled with an alkali solution. The gas exiting the flask was fed to a gas analyzer to record the % CO2 in the exhaust gas stream. The % CO2 absorbed was taken as the % CO2 in the exhaust gas minus the % CO2 in the feed. Theoretical calculations found that as the % alkali in solution increases, the solubility of CO2 decreases. This was verified by experimental data, which found that a 2% alkali solution, by weight, was the ideal solution for CO2 absorption. Current research is focused on using the 2% alkali solution for permanent storage of CO2 via mineral carbonation to produce a value-added product.

May 1, 2012

By G. C. Kachel

During the past two years, there has been an increasing acceptance of process automation among ferrous, non-ferrous and non-metallic rock processing operations in an attempt to keep total unit costs in line in a market situation where labor and material costs are rising almost daily. Previous technical papers (1) (2) (3) (4) (5) have described, in considerable detail, instrumentation and automatic control devices that have been successfully applied in a wide variety of crushing and grinding facilities. While many of the basic control philosophies that evolved almost ten years ago remain essentially unchanged, new components and devices have been developed during the past two years that permit these philosophies to be better implemented in operating plants. Some of these devices and their application will be discussed with particular emphasis placed in describing the basic control philosophy employed as well as some of the hardware or components comprising typical crushing and grinding circuit control systems. Before any instrumentation or automatic control system can be successfully devised for a specific facility, there must be a clear understanding and agreement by supplier and user as to the control system objective. In the case of a crusher feed rate control system, the objective is generally to maximize thru-put of a given finished product size. While this is often the case in a grinding circuit automatic control system, the reasons may be entirely different. Taconite processors whose end product is to be pelletized, generally attempt to control their grind within narrow limits to optimize balling action. Other milling operations are more concerned with obtaining metallurgical liberation and can, in many cases, tolerate wider swings in finished grind.

Jan 1, 1969

By Neal P. Cochran

My talk today is an effort to project our thinking forward a few years to that point in the future when we will be producing gas and liquid fuels from coal. To those of you that are concerned with meeting today&apos;s production quota--my remarks may sound like a Buck Rogers projection. Not so. Although I&apos;m talking about the future, please understand that my thoughts are focused on the near term future. The coal plant of the future will be an energy plant producing energy products to meet the needs of our modern society. This plant is an outgrowth of Government- industry cooperation. Much of the research work that makes such a plant possible was jointly funded, other work was a continuation into development of private research expenditures, other work was performed by private research organizations with Government funding, other work was performed in Government laboratories, both State and Federal. As indicated above, and in the title of my talk, I expect to describe the coal plant of the future. I will describe a plant producing Carbon, Oil, Pipeline gas, and Electricity--Project COPE. This plant copes with the Atomic-Nuclear Group. As stated above, this plant is an energy plant. Energy plants today are large-scale operations. Power plants of 5,000 megawatts are projected, refineries of 500,000 daily barrels are near term probabilities, 48" transcontinental gas pipelines are with us today and 25,000 daily ton mines are here as well. The COPE plant will be of the same general size and require 50,000 - 100,000 tons of coal per day.

Jan 1, 1969

By Jeong-Heum Kim, Jan M. Mutmansky, Y. J. Wang

The simulation of randomness in a system of components is important in certain types of systems analyses. This paper presents procedures for generating ventilation networks that are random in many of their characteristics and which can be used to study the performance characteristics of various mine ventilation network analysis procedures without introducing undue bias as a result of the nature of the network. Among the parameters of a network that affect the efficiency of a network analysis procedure are: (1) the interconnection pattern of airways, (2) the distribution of resistances in the network, (3) the number and location of fans, (4) the fan characteristic curve, (5) the size of the network (number of branches), and (6) the density of the network (number of nodes compared with the number of branches). In the procedures proposed here, a single fan with a fixed characteristic is used to simplify the problem and eliminate the fan as a source of variation. The resistances of the airways, the pattern of interconnection of the airways, and the fan location are randomly chosen in an attempt to eliminate the bias in the performance characteristics of the network analysis methods caused by these parameters. A method of generating biconnected networks while keeping the "randomness" of these other parameters is suggested. At the same time, the size and the density of networks are controlled to investigate their impacts on the performances of the network analysis procedures. The combination of these two variables has been termed the "level of complexity" of the network in this paper. Finally, a summary and conclusions section outlines some characteristics of the networks generated, using the random generation procedures outlined in the paper.

Jan 1, 1991

By G. Papantonopoulos

Natural stones are extensively used for construction purposes since the dawn of human civilization, due to their unique aesthetical and technical characteristics. Their production and consumption has been continuously increasing over the past twenty years worldwide at an annual rate of 8.8%. European countries lead the race of per capita consumption, with Switzerland being in the first place with a consumption of 144.7 m2 per hundred inhabitants followed by Greece, Spain, Portugal, Belgium and Italy. On the other hand, during the period 2001-2002 the generated stone wastes were 110 million tones according to EU data, from which only about 5 million tones were recycled or re-used mainly in the construction industry. These stone wastes the non-natural wastes such as oils or chemicals coming from the equipment and machinery employed for stone extraction and processing, are disposed in the environment, posing serious environmental threat. To achieve sustainable development of the stone sector appropriate methods that will prevent or reduce waste generation and disposal have to be identified and applied. In this work an extensive study of the stone waste management techniques applied in Europe is carried out, in order to identify the Best Available Techniques (BAT) that can be used according to the type of generated wastes and the waste management hierarchy: Waste minimisation, Re-use, Recycling and Disposal. The identification of BAT was performed based on 14 Sustainable Development Indicators (SDI), which were grouped into three categories: environmental, economic and social. The developed final list of BAT includes waste minimisation techniques, eco-management schemes, in-situ treatment and appropriate storage and selection.

Jan 1, 2007

By Vinton A. Garbesi

INTRODUCTION The placing of the monolithic concrete lining of the Bi-County water tunnel illustrates the state of the art in the materials, equipment, methods and productivity available to the industry for this type of construction. This paper describes the management and engineering rationale used by Clevecon, Inc., a subsidiary of S & M Constructors, Inc., Solon, Ohio, in developing the concrete mix designs, the design of the specialized equipment, and the methods used in the manufacture, transport, and placing of the lining. Also discussed are the changes to the reinforcing steel design instigated to facilitate its handling and placing, as well as to enhance the quality of the lining. The intent is to bring to the attention of designers the effects certain design aspects have on the construction of reinforced concrete tunnel linings, as well as indicate the areas where research and development effort should be expended to further reduce costs for this type of construction. GENERAL DESCRIPTION The Bi-County Water Tunnel West is a water transmission main owned by the Washington Suburban Sanitary Commission of Hyattsville, Maryland. The facility was designed by A. A. Mathews Division (formerly STRAAM Engineers, Inc.) CRS Group Engineers Inc., Rockville, Maryland. It is to be utilized as the central feeder of potable water for the northern suburbs of Washington, DC, extending some 4,597 meters from a riser shaft at its western terminus to the eastern interface, with a similar tunnel which extends eastward about 5,180 meters; the majority of its length being under Interstate Highway 1-495. The excavated and finished diameters are 3.8 and 3.05 meters respectively. The reinforced concrete

Jan 1, 1981

By Pieter Berendsen

Lamproite occurs in two locations in southeastern Kansas that are in close proximity to each other. In both locations, the lamproite is restricted to north- east-elongated, ellipsoidal depressions measuring about 3 mi by 1.5 mi. At the surface and in the shallow subsurface, lamproite occurs as sills that were intruded into Middle and Upper Pennsylvanian rocks consisting of shale, limestone, and minor sandstone. Isotopic age determinations by Zartman and others (1967) indicate that the lamproite was intruded during the Late Cretaceous (88-91 my). Drillholes for hydrocarbon exploration down to a depth of about 1,400 ft (top of the Mississippian) and numerous shallow drillholes (mostly 200-300 ft) by the Kansas Geological Survey in the northern portion of Silver City dome helped to understand the structural complexity and extent of the near-surface sills. Numerous radial faults showing small apparent vertical offsets limit the lateral continuation of individual sills. Concentric faults are believed to mark the edge of the depression. Wagner (1954) mapped the geology of Silver City dome in considerable detail and recognized a northward dipping, 120-ft-thick, lamproite sill exposed at the surface along the northeastern edge of the dome. The upper 40-50 ft of the sill weathers olive-brown and has a soft, clayey consistency in which only the phlogopite mica is recognizable. The weathered material has been mined by Micro-Lite LLC since 1982 from the exposed sill in an open-pit that measures about half a mile extending in an east- west direction. The bulk of the material, about 98%, is used as an additive in mineral supplements for cattle feed.

Jan 1, 1999

By Richard R. Klimpel

INTRODUCTION The purpose of this paper is to summarize the current status of reagents used in the mineral industry plus present some current challenges and possible new technologies of the future. Table 1 lists the important families of reagents which, when taken together, constitute at least 95% of the current commercial reagent market. A very approximate estimate of the free world reagent market size in mineral applications is about 1.5 to 2.0 billion dollars (U.S.) using 1985 data. Obviously, to serve such a large market requires the effort of many different types of commercial supply sources. It is estimated that there are over 300 industrial firms in the free world that have a dedicated business/technical structure for supplying reagents related to the mining industry. There are a number of characteristics which are associated with the product families listed in Table 1. Understanding these characteristics helps to provide a realistic economic/technical basis for outlining future challenges in mining chemicals. 1.Essentially all of the products listed are old chemistry in the sense that the molecules have been known and manufactured for at least 25 years. This has not been a highly dynamic field of endeavor from the viewpoint of new product introduction. 2. The greater majority of the products listed can be viewed in commercial terms as "commodity" chemicals, that is, they are available from many sources and the pricing of a some- what generic product generally dominates differences in product quality or uniqueness. With commodity pricing, reagent suppliers significantly reduce research expenditures, loosen product quality somewhat if the applications of the reagents allow, etc. in order to be cost competitive.

Jan 1, 1989