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By Mads Aniksdal

New Nedre Fiskumfoss is a construction project in North Trøndelag, Namsen River. The purpose of the contract is construction of a new hydropower plant, that will phase out the existing power plant in the same waterfall. The contract consists of a tunnel system with cross sections from 16 m2 to 150 m2, powerhouse and transformer in rock caverns, 6 shafts and major works with inlet and outlet below river level. Technical challenges consist of demanding design on rock extraction, cofferdams, solid constructions with challenging design and demanding rebar work, as well as restrictions and unpredictable water flow in a national salmon river.

Jun 13, 2023

By D. C. Dahlin

The Bureau of Mines conducted laboratory batch beneficiation tests on samples from four potential platinum resources in southeastern Alaska to concentrate platinum and other precious metals. Thin Investigation was done as part of the mission of the Bureau to insure an adequate supply of minerals to meet the Nation's needs. Petrographic studies and beneficiation methods including gravity concentration, froth flotation, and magnetic separation were used to determine mineral association and to attempt to concentrate the platinum values with a primary mineral value such as chromite, copper sulfide, or magnetite. A high-graded sample from the Salt Chuck copper sulfide deposit yielded the platinum-group metal concentrate; the maximum grade attained was 0.04 oz Pt and 1.5 oz Pd per ton of high-grade copper sulfide concentrate. The other samples yielded low-grade primary mineral concentrates with low platinum-group values, and/or the platinum-group metals did not concentrate with the primary mineral value.

Jan 1, 1981

By G. C. McCartney, S. J. Kidder

The Helen Mine, of the Algoma Steel Corporation, in the Michipicoten district, Ontario, Canada, has produced more than 6,240,290 tons of iron ore. Prior to and during World War I, 2,823,369 gross tons of brown ore were shipped, and from 1939 to the end of the 1944 season, 3,416,921 gross tons of siderite ore were produced from open-pit operations. Brief descriptions are given of the nature of the ore, the mining methods employed and the manner of treatment of the ore. Shipment of the finished product, known as Algoma sinter, is made to blast furnaces in both Canada and the United States. The iron-ore bodies—i.e., the oxide ores of the Old Helen and the siderite of the New Helen—are a part of a tabular shaped area of iron formation that extends over a length of more than 100,000 ft. and has a maximum width of 1000 ft. The ores are considered to be a product of introduction of iron-bearing material accompanied by replacement of the rocks already present. It is shown that introduction took place subsequent to the development of the major folded structures. It is believed the iron-bearing material emanated from an igneous source. Introduction The Michipicoten mining district derives its name from the Indian word1 meaning "place of bold promontories" or "region of big places," and anyone who has visited this part of Canada will agree that the district is well named. In 1897, there was active prospecting for gold in the district and the Ontario Bureau of Mines2 opened a recording office at the Hudson's Bay post at Michipicoten River. In the summer of 1897, Ben Boyer, probably searching for gold, discovered an outcrop of brown iron ore at the east end of a small lake, less than 8 miles, in an air line, northeast of the nearest point on Michipicoten Harbour. In the following year, extensive surface exploration and diamond drilling disclosed a commercial body of nonbessemer brown ore, possibly 700 ft. long and 200 ft. wide, of about the following analysis:3 Fe (natural), 57.15 per cent; S, dried at 212°F.. 0.113; SiO2, dried at 212°F., 4.00; P, dried at 212°F., 0.125. The property (Figs. 1-3) was taken over by E. V. Clergue and ultimately was transferred to the Algoma Steel Corporation. The Algoma Central Railway shortly afterward built its line from Michipicoten Harbour to the mine, together with an ore dock at the Harbour. Thus, within three years of its discovery, the mine had adequate shipping facilities and a market for its ore. Production of Brown Ore and Pyrite The first shipment of brown ore was made in July 1930. By 1939, the mine was shipping at the rate of 170,000 long tons

Jan 1, 1949

By S. J. Kidder, G. C. McCartney

The Helen Mine, of the Algoma Steel Corporation, in the Michipicoten district, Ontario, Canada, has produced more than 6,240,290 tons of iron ore. Prior to and during World War I, 2,823,369 gross tons of brown ore were shipped, and from 1939 to the end of the 1944 season, 3,416,921 gross tons of siderite ore were produced from open-pit operations. Brief descriptions are given of the nature of the ore, the mining methods employed and the manner of treatment of the ore. Shipment of the finished product, known as Algoma sinter, is made to blast furnaces in both Canada and the United States. The iron-ore bodies—i.e., the oxide ores of the Old Helen and the siderite of the New Helen—are a part of a tabular shaped area of iron formation that extends over a length of more than 100,000 ft. and has a maximum width of 1000 ft. The ores are considered to be a product of introduction of iron-bearing material accompanied by replacement of the rocks already present. It is shown that introduction took place subsequent to the development of the major folded structures. It is believed the iron-bearing material emanated from an igneous source. Introduction The Michipicoten mining district derives its name from the Indian word1 meaning "place of bold promontories" or "region of big places," and anyone who has visited this part of Canada will agree that the district is well named. In 1897, there was active prospecting for gold in the district and the Ontario Bureau of Mines2 opened a recording office at the Hudson's Bay post at Michipicoten River. In the summer of 1897, Ben Boyer, probably searching for gold, discovered an outcrop of brown iron ore at the east end of a small lake, less than 8 miles, in an air line, northeast of the nearest point on Michipicoten Harbour. In the following year, extensive surface exploration and diamond drilling disclosed a commercial body of nonbessemer brown ore, possibly 700 ft. long and 200 ft. wide, of about the following analysis:3 Fe (natural), 57.15 per cent; S, dried at 212°F.. 0.113; SiO2, dried at 212°F., 4.00; P, dried at 212°F., 0.125. The property (Figs. 1-3) was taken over by E. V. Clergue and ultimately was transferred to the Algoma Steel Corporation. The Algoma Central Railway shortly afterward built its line from Michipicoten Harbour to the mine, together with an ore dock at the Harbour. Thus, within three years of its discovery, the mine had adequate shipping facilities and a market for its ore. Production of Brown Ore and Pyrite The first shipment of brown ore was made in July 1930. By 1939, the mine was shipping at the rate of 170,000 long tons

Jan 1, 1949

By AIME AIME

AMERICAN participation in the World Engineering Congress in Japan will be generous. Nearly seventy papers have been prepared and for- warded for printing and the A. I. M. E. is well represented in the list. At our San Francisco meeting four of these will be briefly reviewed by the authors for the benefit of those who are unable to go on to Tokyo. They constitute a group dealing with the present economic status as seen by engineers of the world's iron, coal, petroleum and non-ferrous metals. Messrs. Leith, Smith and Tryon, Requa, and Probert have written papers that constitute a notable series. Messrs. Jeffries, Sweetser and Kinney, and other Institute members have written papers dealing more closely with technologic progress. The latest list of delegates and members is printed below, names of A. I. M. E. members being set in italics.

Jan 1, 1929

By Tuneo Funahashi

Sumitomo Shisaka Works has been treating EAF(Electric Arc Furnace) dust to recover zinc and lead in the Waelz Kiln process. Since its commencement of operation in 1977, many technical improvements have been successfully made to increase the production capacity and the zinc recovery rate. The EAF dust charge to the Waelz Kiln was increased from 35,000tly to 120,00OtIy, and the production of zinc oxide now amounts to 40,000tly. The zinc content in the clinker was decreased from 5% to less than I%, by the optimization of the kiln heat pattern with no accretion trouble. And the clinker has become more a valuable raw material for steel making. This paper describes the above progress ofthe SMM Waelz Kiln process operation at the Shisaka Works.

Jan 1, 1998

By J. G. Mieczaniec

"A key element for a successful mining operation is the grinding circuit. It must be reliable, maintainable and must perform to or above design capacities for 95% of the time. Once chosen and installed major modifications are either prohibitive or very expensive. The selection of mills and drive system is probably the single most important decision made within the concentrator complex.Economic studies revealed that the optimum expansion for Lornex was a 68070 increase in plant throughput. This indicated that the new mill would have to be larger than the existing 32-foot mills.The Lornex ore has a wide range of hardness which has a great influence on mill throughput (Table 1). To smooth out the fluctuations, a blending program ha s always been in effect at the mine, coupled with ball charge control for the primary mills. As can be appreciated, an optimum balance is difficult to achieve. A sudden change to so ft ore with a high ball charge puts the mill into jeopardy with a constant speed drive.The blending philosophy would continue after the expansion, but with the addition o f a second primary crusher, it was envisaged to have the new mill process harder ore to maintain production targets. In theory, the new mill would have a proportionally larger ball charge than the existing mills.This scheme makes the new mill vulnerable for processing so ft ore for a fixed speed mill. Thus, variable speed seemed an attractive option.In early 1979 prominent mill manufacturers were invited to submit proposals for the new mill. Fixed and variable speed mills were to be considered with mill size ranging from 32-foot to 36-foot diameter. The proposals were to include the drive, ball charge, % critical speed, couplings, gears, etc. - the complete package. The recommendations were variable with most manufacturers submitting several alternatives. Recommended mill speed varied from 68% to 78% critical. The concept of variable speed was becoming more attractive, Lornex ultimately decided on a twin DC motor drive system for a 34-foot diameter mill.After start-up it was discovered that best throughput occurred at 78% mill critical speed or top speed of the drive motors. The motor speed range was adjusted upward from 186 to 200 rpm. Today the mills operate at 79% critical or a motor speed o f 193.5 rpm.Clearly the selection of the variable speed mill allowed the flexibility to optimize throughput."

Jan 1, 1985

By Carl R. Peterson

The Rapidex continuous drill and blast tunneling concept utilizes a unique spiral blasting pattern that permits efficient performance with relatively small single shots, while at the same time directing major blast fragments at right angles to the tunnel axis. The concept's self-shielding geometry permits the design of a lightly shielded machine that can stay at the tunnel face firing frequent small blasts to provide rapid, virtually continuous advance. This paper describes Phase III of the development program (supported under Bureau of Mines contract H0252047) in which the "front end" of the machine?drilling loading, and shooting components, together with the shield--was fabricated and field tested underground at the White Pine Copper mine, Michigan. One of the major accomplishments of the Phase III effort was to develop a fully remote controlled loading and initiation system in which explosive slurry is pushed, through a hose into the blasthole by a small water-driven piston carrying the blasting cap. The cap is ignited via an induction coil just prior to entry into the borehole, after which a delay permits complete -withdrawal and shielding of the loading hose. The ultimate objective of the present Bureau-sponsored program is to evaluate the feasibility of mechanizing hard rock mining operations, such as development to a point where drilling, loading, shooting, and mucking can proceed simultaneously and result in increased productivity.

Jan 1, 1977

By Garth M. Crosby

Seven mines with important production records in the Coeur d'Alene lie adjacent to the Gem stocks -the Frisco (Gem), Hercules, Interstate, Rex (Sixteen to One), Success (Granite), Sunset, and Tamarack. Old records are incomplete, but avail- able data given in Table I show these mines have produced 10,550,721 tons of ore containing more than 50 million oz of silver, more than 1.5 billion lb of lead, and about 1 billion lb of zinc (approximately 1.25 million tons of lead and zinc combined). Average ore grade is 4.8 oz of silver per ton, 7.2 pct Pb, and 4.6 pct Zn. This impressive production represents about 12 pct of the District's yield. At present metal prices, with modern beneficiation, the gross value would be more than $400 million.

Jan 7, 1959

By F. R. Hensel

THE alloy under discussion is a nickel-silicon bronze and is one of many age-hardening or precipitation-hardening FIG. I.-EFFECT OF QUENCHING AND AGING TEMPERATURES ON HARDNESS OF TWO TYPICAL NICKEL-SILICON BRONZES, NO. 2351 AND No. 2362. copper-base alloys. The hardening con-stituent is a nickel-silicon compound.1 The quenching temperature necessary to pro-duce hardening by a subsequent aging treatment is a function of the composition and extends from about 700'C. to ()50'C.; the aging temperature range extends from 400° to 600°C. The work carried out by the authors of this paper was confined to cast alloys having compositions within the ranges of 1.5 to 3.00 per cent Ni; 0.4 to 0.75 per cent Si; balance, copper.

Jan 1, 1940

By M M. M LT Tassinari, A B. Braz, L M. SantÆAgostino, C Ulsen

Several mineral resources have been recognised to alkaline igneous rocks. In general, these mineralisations present low P grades, so a complex concentration process is required to achieve commercial grade concentrates. This process is guided not only by the ore characteristics, such as apatite grain size and liberation degree, gangue minerals and slimes content, but also by different apatite varieties, iron oxi-hydroxide surface coating and roughness. The main techniques applied to apatite and phosphate ore characterisation, such as optical microscopy, cathodoluminescence (CL) microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), surface techniques and magnetic separation are discussed, aiming to evaluate distinct apatite varieties and their technological behaviour.

Jan 1, 2008

By Robert J. Linney

IN the latter part of the year 1943, it was decided to experiment with diamond-drill blast holes in the Old Bed magnetite mine at the Mineville mines of the Republic Steel Corporation, in sections of the ore body where vertical dimensions were large and where development for sublevel bench stopes had already been done. Other possibilities of application for this drilling method were in the reclamation of old floors and pillars in the pitching folds of the Lower Old Bed ore body and in the reclamation of large vertical pillars in the " 21 " Bonanza-Joker ore body. The cross sections and views of the two ore bodies will show the conditions to which the diamond-drill method has been applied. The Lower Old Bed magnetite ore body is lenticular and dips approximately 30° toward the southwest and strikes generally southeast and northwest. An intensely folded structure, which pitches generally on an axis approximately at right angles to the strike, is continuous from the uppermost old workings down to the present bottom of the mine, and probably continues with depth. On successively lower levels this folded structure becomes greater in vertical dimensions and the two folds are closer together in a horizontal dimension. As shown in Fig. 1, this folded structure gives to parts of the ore body considerable vertical dimensions, which provide areas that were developed for sublevel bench stoping above a slushing drift, as shown in Fig. 2. It was in one of these previously developed sublevel bench stopes, No. 26 on the 1185-ft. level, that the diamond-drill blast-hole method was applied for mining the upper sublevel. The lower sublevel was underhand-bench-drilled to the finger raises of the scram drift below. The roof of this stoping area began to break and spall on the lower sublevel, causing the roof to become inclined. Along the hanging wall of the stope this reached an elevation about half way between the two sublevels. A smooth schistose seam in the hanging wall causes the ore to break away freely. Therefore, if bench mining had been carried on in the upper sublevel, a dangerous condition of poorly supported benches would have resulted. When the drillers were slashing across the sublevel to footwall and hanging wall to make a bench, spalling roof of the opening below would probably have carried away part of the bench, and would have left a dangerous place in which to continue underhand benching. A 6 by 8-ft. raise had been driven between the lower stope and the upper sublevel about 200 ft. from a manway. It was decided to use this raise for a starting cut and to arrange holes as shown in Fig. 3, so that a slot would be opened across the ore body between the footwall and hanging wall. This slot would then be used for the purpose of breaking into the ore; by blasting vertical rings of holes drilled at right angles to the axis of the pitching folds as nearly as possible. Layouts of this slot drilling and the rings adjacent are

Jan 1, 1945

By Zhuo Sheng

We have designed a high-temperature Raman micro-furnace and cell that is suited for the electrochemical process study of the NO3 − in molten NaNO3– KNO3 (fraction of NaNO3 50 wt%) salt. During the cycle voltammetry and constant potential electrolysis process, the Raman laser beam was focused near the electrode; subsequently, the Raman spectra are obtained and the reduction process of NO3 − is analyzed. In the CV cathodic scan process, the new peak attributed to the ν1 mode of NO2 − emerges, and the peaks assigned to superoxide ions (O2 −) and peroxide ions (O2 2−) are not found. In the constant electrolysis process, the peaks at 1130 and 800 cm−1 appear when the potentials are between −2.0 V and −3.2 V (vs. Pt). The results show that when the NO3 − is reduced in molten the NaNO3–KNO3 mixtures, the reduction product O2− cannot stably exist, and O2− will react with NO3 − to form of superoxide ions (O2 −) and peroxide ions (O2 2−).

By T. D. Yensen

EFFECT OF ELEMENTS ON MAGNETIC PROPERTIES OF IRON THE elements aluminum,1 arsenic,2 silicon,3 tin2 and vanadium,4,8 when used in relatively small amounts as alloying elements, seem to have a beneficial effect on the magnetic properties of iron-i. e., they increase the maximum permeability and decrease the coercive force-whereas there are definite indications that boron,5 carbon,6 nitrogen,7 oxygen,8' phosphorus,6 sulfur6 and titanium,4 as well as the metals of and adjacent to the ferro-magnetic group, nickel,9 cobalt,10 copper,11 and manganese,6 have a detrimental effect on these properties. The effects of calcium4 and magnesium4 are small, if any, while the effect of chromium 12 in small amounts is unknown and in large amounts is generally detrimental.

Jan 1, 1931

By Robert B. Parsons

"This article addresses the relationship between mine evaluation, the tax system, and economic risk. It is based on a paper presented by the author at recent seminars in Moscow and Tashkent on the subject of mine evaluation.IntroductionTaxation can have a strong influence on the feasibility of a mining project. For the most part, because metal prices are determined on a global basis, the mining concern is not able to pass on to its customers any portion of taxes which the concern has to pay. Taxes are a direct charge against the project. The purpose of the article is to highlight the various ways whereby different taxes can affect the financial viability of a mining operation.The first part of the paper identifies different forms of taxation, and the second part of the paper addresses the different forms of taxation in terms of risk analysis and impacts on the mining project. Finally, the third part of the paper makes brief mention of using the taxation system to provide incentives with respect to investment in mining activities."

Jan 1, 1993

By R. Venugopal, V. K. Saxena, S. K. Tripathy

"This study was carried out to understand the impact of variation in material morphology on the efficacy of microwave pretreatment. Three different types of mineral matter – coal, iron ore and manganese ore – were treated with microwaves at different energy levels, from 180 to 900 W, for different time durations of one to five minutes. The treated samples were subjected to microscopic, milling and liberation studies. Coal is a porous and amorphous material with low dielectric constant, and grinding of the microwave-pretreated coal samples resulted in an 18.18 percent reduction in the 80 percent of passing particle size, or d80, and a 17.1 percent increase in carbon recovery. The microwave-pretreated soft and friable manganese ore samples showed a 47.82 percent reduction in d80 during grinding and higher manganese recovery of 42.46 percent during liberation analysis. The microwave pretreatment and milling of hard and banded iron ore reduced the d80 by 20.83 percent, but no improvement was observed in mineral liberation. Coal showed better results during treatment at lower energy levels of 180 W for one to three minutes, whereas the minerals needed higher energy of 900 W for five minutes. Particle size analysis indicated rapid size reduction up to an energy input of 25 Wh. This effect diminished with increased energy input.IntroductionComminution is an important unit operation in mineral processing plants for the purposes of size reduction and mineral liberation. But most comminution technologies are energy inefficient and only a small amount of energy is consumed in real size reduction, with the rest wasted. High-grade mineral resources have been exploited on a large scale for the last century, and the upgrading of low-grade resources is now required to fulfill the needs of industry. Pretreatment methodologies for comminution will play a crucial role in the upgrading of low-grade mineral resources. Researchers have studied various pretreatment methods to develop an energy-efficient and techno-economically viable solution to improve mineral liberation and product fineness with minimum energy consumption. Most of these studies were focused on the use of chemical additives, thermal, ultrasonic and microwave treatment, and electric disintegration (Klimpel and Austin, 1982; Norgate and Weller, 1994; Gaete-Garreton, Vargas-Hermandez and Velasquez-Lambert, 2000; Wilson et al., 2006; Kumar et al., 2010; Wang, Shi and Manlapig, 2011; Singh et al., 2012)."

Jan 1, 2017

By Fangting Dong

The broken rock zone (BRZ) and the tunnel support theory are investigated. The relationship between the BRZ and the related factors, the interaction between the BRZ and supports, and the function of supports are analyzed in detail based on the authors' underground observations and model taste. A summary of the application of the BRZ theory in the past is also presented.

Jan 1, 1988

By Robert T. Ault

The nature of fracture in unnotched tensile and notched tensile sheet and round specimens and V -notched and precracked Charpy-type sheet specimens of both wrought stress -relieved and re-crystallized molybdenum was investigated over the temperature range of -78° to 300°C. The sharp rise in fracture stress, for unnotched tensile samples, as the temperature is increased above the brittleness transition temperature (Tb), is found to be a result of an increase in flow stress due to plastic constraint and an increased strain rate which results from the onset of necking at Tb . Quasi-brittle fracture in notched tensile samples is found to occur when the tensile stress at the elastic-plastic interface, beneath the root of the notch, reaches a maximum critical value, which is independent of test temperature over the range from —78° to 25°C, but dependent on microstructure. In the temperature range between 150° and 300°C, unnotched tensile and notched tensile samples alike are found to fracture by a ductile fibrous tearing process which is discontinuous in nature, as a result of the competition between the processes of tearing, through continued plastic flow, and local work hardening. Results from the V-notched and fatigue-cracked Charpy-type impact tests demonstrate that crack initiation is the governing factor in the low-temperature (-78° to 25°C) fracture process for molybdenum. In recent years, there has been considerable interest, and a commensurate number of investigations, concerning the duc tile-to-brittle transition in refractory metals. There has not developed, however, a satisfactory explanation for the uniaxial tensile fracture-stress transition which accompanies the well-known ductility transition. This matter therefore warranted investigation. In a similar manner, the increased importance of notched tensile strength values in evaluating materials and in design criteria requires a better understanding of the factors which control the fracture behavior of notched tensile samples. In a previous investigation1 of the nature of initial yielding and fracture in notched sheet molybdenum at room temperature, it was suggested that plastic constraint was the controlling factor in governing the fracture behavior of notched samples. The final portion of this investigation was concerned with the fracture toughness of molybdenum. Of particular interest was the comparison of effective surface energies for fracture in V-notched samples with fatigue-cracked, Charpy-type samples in order to ascertain the relative importance of the initiation and propagation phases of the fracture process. MATERIALS AND TEST PROCEDURE Sheet tensile, notched tensile, and V-notched Charpy specimens were prepared from 50-mil, stress-relieved molybdenum sheet.* Half of these specimens were vacuum-annealed for 1 hr at 1200°C and 7.5 x l0-5 Torr and furnace-cooled to produce a relatively uniform grain size of 0.30 mm diameter. Round notched and unnotched tensile specimens were prepared from warm-rolled and swaged 5/8-in.-diam bar.* These specimens were vacuum-annealed for 1 hr at 1350°C and 5 x lom5 Torr and furnace-cooled to produce a grain diameter of 0.11 mm. Material analyses in ppm were: C N O H Sheet 290 10 4 1 Bar 50 30 30 2 The unnotched tensile sheet specimens had a 1/4-in. gage width and a 1-in. gage length. The unnotched tensile round specimens had a 9/32-in. gage diameter and a 1-1/4-in. gage length. The sheet and round notch tensile specimens are shown in Fig. 1. All of the notched tensile specimens tested were tandem-notched in order to study the location and mode of fracture initiation. The tandem-notched specimens were carefully machined so that the largest variation in notch depth on a single specimen was 0.001 in. Thus, when fracture occurs, the extent of plastic deformation that exists in the un-fractured notch section is that which exists just prior to fracture. All of the tandem-notched sheet specimens were electrolytic ally polished and chemically etched prior to testing. The V-notched Charpy-type specimens machined from the 50-mil sheet material had the standard dimensions of 2.125 in. long, 0.394 in. deep, and a 0.010-in. root radius. The unnotched tensile and notched tensile tests were conducted over the temperature range of -78° to 300°C, in a 10,000-lb Instron Universal Testing Machine, at a constant crosshead speed of 0.020 in. per min. The V-notched Charpy-type

Jan 1, 1964

By Adam Hacker

In early 1937, the Ohio River elevated to its highest levels leading to devastating flooding in Louisville, Kentucky. Today, that historical flood, also known as the Great Flood of 1937, is still the flood of record for the area. In an effort to re- duce flooding risk to the population, the Flood Control Act of 1937 was passed to strengthen Louisville's re- silience against future flooding. This triggered the U.S. Army Corps of Engineers (USACE) to construct the Louisville Metro Levee System, which comprises 26.1 mi (42 km) of concrete floodwalls and earthen levees with 16 flood pump stations. One of those flood pump stations was the Paddy's Run Flood Pump Station, which was built in the 1950s, in the western portion of Louisville. That flood pump station was located at an existing stormwater outfall that conveys the stormwater from the western metro- politan area under the levee to the Ohio River. The stormwater flows through the outfall by gravity when the Ohio River is not elevated. When the river is elevated, the flood pump station becomes active after a flood gate at the end of the outfall closes. This is necessary because with- out the flood gate, the Ohio River would backflow into the outfall causing inland flooding. When the flood pump station is active, the stormwater gets pumped over the levee embankment through discharge pipes into the Ohio River. Stormwater can collect in a ponding area and backup during intense rainfall events when the inflow to the flood pump station exceeds the capacity. Recently, Louisville and Jefferson County Metropolitan Sewer District (MSD), which now operates and main- tains the levee system, determined the need to upgrade the existing Paddy's Run Flood Pump Station's capacity to reduce the risk of interior flooding. MSD determined the new flood pump station would need to increase existing capacity from 875 million to 1,900 million gal (4 to 8.6 billion L) a day to account for a 2035 projected storm event, which is a 10-year, 24-hour storm event of 5.0 in (127 mm) in 24 hours. Due to the age and complications associated with up- grading the existing pump station, a new pump station was selected as the preferred approach. In 2021, MSD

Nov 1, 2025

By Eugene N. Cameron

Pegmatites of these areas have become important sources of beryl and lepidolite and have yielded cassiterite, columbite-tantalite, and other minerals. Examination of about 60 of these pegmatites leads the author to question the opinion of earlier investigators that the concentrations of beryl, lepidolite, and columbite-tantalite found have mostly formed by hydrothermal or pneumatolytic replacement of previously formed quartz-feldspar pegmatites. The author concludes, on the contrary, that present knowledge of the occurrence of minerals in zoned pegmatites can be applied to prospecting and mining of pegmatite deposits in these two areas of South West Africa. PEGMATITES occur in abundance in certain areas of South West Africa and in adjacent parts of northern Cape Province in the Union of South Africa. Some of the pegmatite deposits were prospected before World War I, and intermittent mining was done during the period between the two World Wars. The deposits of the Jooste lithium mines became an important source of lepidolite, and beryl, columbite-tantalite, wolframite, and other minerals were produced. Since World War II prospecting and mining have been carried on vigorously, with the result that South West Africa produced nearly 3000 tons of beryl during 1949 through 1953, together with more than 40,000 tons of lithium minerals, chiefly lepidolite and petalite. Small amounts of tantalite, columbite, and other minerals have also been produced during the postwar period. Most of this mineral production has come from two pegmatite areas roughly outlined in Fig. 1. One is the Karibib-Omaruru area of north central South West Africa. The second is the northeastern part of the Orange River pegmatite area, which extends into adjacent parts of Namaqualand, in northern Cape Province of the Union of South Africa. The writer visited the two pegmatite areas in July 1951. The visit was brief. but it gave an opportunity to compare some of the' pegmatites of these areas with those studied and described in detail by many investigators in the U. S., Brazil, and Canada during and since World War 11.'-l' The writer has attempted to determine, in a preliminary way, whether the concepts of internal structure and distribution of minerals in pegmatite bodies developed out of these studies are applicable to prospecting and exploration of pegmatites in South West Africa. Previous Work In an important series of papers (1929 to 1942) T. W. Gevers, H. I?. Frommurze, S. H. Haughton, G. K. Joubert, and other geologists of the Geological Survey of South Africa described and discussed the pegmatites of the two areas.*-" These works are the principal sources of information on the pegmatite mineral deposits of South West Africa. The investigations showed that in the two areas pegmatites are profusely distributed in pre-Cambrian rocks. These rocks are meta-igneous and metasedimentary units that have been folded and subsequently invaded by younger pre-Cambrian granites and by other igneous rocks. The pegmatites are considered to be genetically related to the pre-Cambrian granites. Pegmatites occur in the granite bodies themselves but are most abundant in the surrounding metamor-phic rocks, a pattern repeated in many pegmatite districts of the world. The origin of the pegmatites and the factors controlling the occurrence of mineral deposits in them were discussed at length by Gevers and Frommurze (1929)" and later by Gevers 14, 15 pp. 41-51, Ref.

Jan 1, 1956