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By C. E. Lesher

Two processes for agglomerating fine sized ores with low temperature coke are described. One process (Orcarb) agglomerates ores with limited amounts of carbon; the other (ore-carbon pellets) pelletizes fine sized ores, using low temperature cokes as the binder. Data are presented on the products obtained when taconite, magnetite, and hematite concentrates and several titanium oxide ores were used. REDUCTION of finely divided oxide ores has long been a major metallurgical problem. Various methods of agglomerating, notably briquetting, sintering, nodulizing, and pelletizing, have been developed and are in industrial use. Carbon is the usual reducing agent for oxide ores and attempts have been made to agglomerate fine ores with coking coal in order to get the metallurgical advantages of intimate contact and increased particle sizes suitable for subsequent smelting or reduction.1-3 For the past three years, research has been in progress on two processes for combining fine sized ores with reactive carbon in the form of low temperature coke. By one process, designated Orcarb, the ore is coated with coke carbon in amounts limited to that required for reduction and the result is an appreciable but limited increase in product particle size over that of the original ore. The second process, called ore-carbon pellets, produces pellets of fine ore bound by low temperature coke. The first objective was to develop a process for combining an oxide ore with only enough carbon for its reduction, the amount being that derived from the simple reduction equations. The carbon (that amount theoretically required for the reduction of the oxides in an agglomerate with ore), calculated to CO, ranges from 10 pct for zinc calcines Or phosphate Ores to 21 pct for rutile and 26 pct for silica. The carbon required for reducing iron oxides falls between the extremes—10 and 26 pet' When the carbon in the agglomerate is low temperature coke, reduction by hydrogen may be expected to take place, thus modifying the calculated carbon require- ment. On the other hand, in practice, an excess of reducing agent over that required in theory is normally used. Screen sizes of three iron ores on which the greater part of the experimental work was performed are given in Table I. Most of the testing was done with Freeport (Renton Mine) coal, but Pittsburgh and Elkhorn bed coals were also used. The first objective was to agglomerate the ore with sufficient low temperature coke to provide carbon for reduction, i.e., in the range from 10 to 25 pct. This was accomplished by preheating the ore, mixing with pulverized coking coal, and completing the coal carbonization in a plain steel rotating retort. The pilot retort, as it is now constituted, is shown by diagram in Fig. 1 and photograph, Fig. 2. Ore is fed into the upper kiln by a screw; it is heated to 900° to 1100°F by direct flame and it is then discharged into an insulating hopper from which it goes

Jan 1, 1956

The probability of detachment of quartz particles from air bubbles during bubble oscillations was investigated by means of a vibration method. Theoretical calculations of the detachment force based on the work of Nutt and Schulze for a single spherical particle show a correlation with the experimental results described. However, the forces that were determined experimentally were considerably lower than the theoretically derived values. Some of the factors which were expected to affect the probability of detachment, such as particle size, bubble size, collector concentration and vibrational acceleration, were also investigated

Dec 1, 1991

By T. Narita

The diffusion barrier coating system (DBC system) was designed to suppress interdiffusion between alloy substrate and coatings in addition to ensuring slow oxide growth at high temperatures. In this report the concept of the DBC system will be introduced, and the results obtained for various heat-resistant alloys are presented. In this DBC system the s-phase of the Re-Cr-Ni system was selected as the barrier and is formed by electroplating Re-Ni and Ni films from aqueous solutions, followed by Cr and/or Al pack cementations. A typical DBC system consists of Ni-base superalloy / triple s-Re based alloy layer / ?’-Ni3Al and/or ß-NiAl (with or without Pt addition) / a-Al2O3. It was found that the DBC system maintained its structure for long time exposures because the s phase has tie-lines with the ? and ?’ alloy substrate and the ?’ and/or ß coating. The s-Re based alloy can suppress both the inward Al diffusion and the outward diffusion of alloying elements. The DBC system was successfully applied to various heat-resistant alloys such as Ni-Mo and Fe-Cr-Al based alloys, and these alloys with the DBC system were creep-deformed slowly under external applied stresses. A simultaneous diffusion coating process for Al and Hf was developed using Hf+NH4Cl+Al2O3 pack cementation. To obtain reliable and long-life coatings the combination of alloy substrate, coating, and external scale should be considered as a total system, to optimize oxidation resistance, structural stability, and mechanical properties.

Jan 1, 2010

By E. Yigit

Hydrometallurgical production of zinc from concentrates is generally carried out by H2SO4 leaching. For the smooth operation of this process, some harmful components must be removed from the leach solution before the electrolysis stage; MgO is one of these compounds. Zinc concentrate samples from the Mount Isa mines were used in leaching tests. Leaching tests with an aqueous solution of H2SO4 and SO2 gas were carried out at various temperatures, pH levels and leaching durations. While duration and the pH value of the solution were effective parameters in H2SO4 leaching, temperature and pH were more effective in SO2 leaching for the removal of MgCO3 and CaCO3. Removal of MgCO3 and CaCO3 was generally achieved at low pH values. The results show that SO2 gas can be a good alternative to sulfuric acid in the leaching of MgCO3 and CaCO3

Jan 1, 2010

By J. F. T. Agapito

Significant economic benefits can result when rock mechanics is applied within a practical framework and integrated within the other engineering functions of the mine organization. This requires management support and understanding of rock mechanics as a practical tool to help attain high standards of safety, productivity and resource recovery. For such an approach, a long-term geotechnical program is needed in most operations to build an adequate data base and to ensure that design and ground control issues are handled in a cost-effective manner. This paper presents a summary of four case studies where significant economic benefits were realized with the help of rock mechanics. Although cost savings were not computed, the economic benefits are obvious and clearly impacted the mine operations favorably.

Jan 1, 1990

By Eiki Ono, Atsushi Yamatodani, Shigeru Sunagawa, Yasushi Takasaki, Atsushi Shibayama, Yasunori Higuchi

"During metallurgical processing of non-ferrous metals, smelting residue (inc. smelter slag, flue gas and so on) is inevitably generated as secondary product.In this research, some experimental feasibilities were investigated to recover/remove Cu and As from the residue. Primarily, the removal of As and volatilized materials from the residue was examined by pyrometallurgical treatment (dry-process). In the second stage after treating the residue with a dry-process, leaching and solvent extraction as hydrometallurgical treatments (wet-process) were also investigated by using H2SO4 solution as a two stage leaching treatment, to dissolve various metals from the leach residue. Then, solvent extraction was examined by using LIX-84I as an extractant to recover and separate Cu from impurities from the final (2nd) leached solution. For the leaching stages, the removal of 90 % As and the leaching rate of 85 % Cu could be achieved by 0.25 mol/l and 1.0 mol/l H2SO4 solution, respectively. On the other hand, the extraction of over 90 % Cu and stripping was carried out by solvent extraction. 1. IntroductionIn metallurgical process for non-ferrous metals, smelting residue (inc. smelter slag, flue gas and so on) is inevitably generated as secondary product, i.e., flue dust, slug and so on. The smelting residue includes some useful metals and undesired toxic materials; Cu, Pb, Ca and As, etc.In Japan there is one undisclosed place stockpiled with 10,000 ton of smelting residue from abandoned smelters about 25 years ago. Therefore it is necessary to reduce the residual amount for space and environmental protection including water treatment by separating and removing toxic materials."

Jan 1, 2008

By Edgar F. Cruft

INTRODUCTION It is sometimes said that "mines are made, and not found." I rather doubt that the exploration geologist would be overly sympathetic to that statement, and, of course, like most one-liners it is only partly true. Access to different financial markets are important at the mineral prospect stage. The modern mine financier has a much more complex, and interesting, job than the financiers of an earlier era, for example, the Canadian financiers of the 40's and 50's who had one simple set of options; i.e. float a company, promote it, and sell an equity stock issue, and then promote it some more. QUALITIES OF A FINANCIER Because technical people are seldom taught financing in their basic training, and because they are usually not involved in it until at quite a senior level in their careers, the whole field often acquires a certain mystique. The engineering professions have too often believed financing is the province of the accountant or financial executive and just as we in the technical world are often too quick to bristle if the latter try to tread on our domain, the opposite can just as easily be true. Unfortunately, this is another example of a compartmentalized individual, and that is one thing the successful financier cannot be. However, to be a successful financier one does not need extensive training or experience in accounting or finance. In fact it can sometimes be a disadvantage to get too buried in working only from the standpoint of discounted cash-flow analyses, ROI's, etc. It must be stressed, however, that one had better know how these analyses are made, and be knowledgeable in understanding a balance sheet, and have a good understanding of financial terminology. The difference between a simple project-type debt financing with a commercial bank and a more inventive and creative financial package comes from an intuition and an experience relating to risk-reward factors. The most important element is "common-sense", based on knowledge and experience. The goal is structure a financial package that fits the project, and in so doing it is important to recognize that it must fit within the limitations of the group supplying the money. I find insensitivity to recognize these constraints the most common mistake made in the field. Put yourself in the other person's place and understand his sources of funds and financing limitations. The engineer has an advantage in financing, as he or she has (or should have) a better idea than anyone of the value of the product, be it the mine, prospect, or company i.e. the intangible or potential worth which cannot be put on a pro-forma. He also knows, or should know, the risks involved. Two projects might look the same on paper, but a good financier must have a sense of when to take whatever deal he can get, and when to hold out based on his evaluation of future developments. It is essential to have a good sense of commodity values and trends, trends affecting the general economy (money supply, interest rates, effects of energy costs, etc.), and political considerations. He must also have a good understanding of the science and art of taxation as deals can often be financed using the government as a silent and unwitting partner by proper use of the tax laws. WHEN TO SEEK FINANCE The first critical decision to make in financing a mineral prospect is "when". At the exploration level, when it is only a dream in the geologist's eye, the alternatives are more limited than when it is a fully-engineered project. The "when" decision depends on how much in internal funds the company has to play with, and how desirable it is to invite financial participation to spread the risk. Assuming that decision is not taken out of lack of money, no one can categorically say when to do it. There is

Jan 1, 1985

By J. L. Jambor, M. J. Baker, M. J. Logsdon

"Abstract - Prior to the development of the Diavik Diamonds Project, baseline studies were conducted to determine the geochemical characteristics of four kimberlite orebodies as an aid in the design of both the water-management system and the facilities for containment of processed kimberlite and ore stockpiles. Materials tested included field samples of volcaniclastic and pyroclastic kimberlite, processed kimberlite (i.e., kimberlite ore which had been screened and washed as part of the processing procedure), and sedimentary mudstone (a minor xenolithic unit which was assimilated during kimberlite emplacement). Approximately 200 samples of kimberlite materials were collected as part of the geochemistry program. Test-work included whole-rock chemical analyses, acidbase accounting, kinetic leach tests using columns, and mineralogical analyses. Diavik kimberlite has major oxide and trace-element concentrations consistent with global averages for kimberlite. The mean total-sulfur content of the kimberlite material is 0.22 wt% S, but with a significant range. The kimberlite has an excess of carbonate minerals over sulfide minerals (average CO2 = 4 wt%, present mainly as calcite), and has a mean neutralization potential of 311 kg CaCO3 equivalent/tonne. A reactive form of framboidal pyrite associated specifically with the mudstone xenoliths is the primary source of sulfide-sulfur. Long-term kinetic tests confirmed the preliminary interpretations that were made from the static-test results. Kimberlite and processed kimberlite are net acid-consuming materials that produce alkaline drainages and have low but detectable leaching rates for SO4 and specific trace metals such as Al, Co, Cu, Ni, and Zn. If segregated from the kimberlite, mudstone xenoliths are acid-generating (pH = 3) and produce an effluent with elevated concentrations of SO4, Fe, Al, Cu, Ni, and Zn. The study demonstrates that xenolithic units in Diavik kimberlites have an important effect on the environmental geochemistry of the ore rock. The mineralogy and aqueous geochemistry of the kimberlite materials are such that they may not be suitable for general earthworks or as an alkaline agent and should report to an engineered facility to protect site water quality."

Jan 1, 2001

By Linda C. White

The use of red mud, a waste product of the ?Bayer? process for bauxite refining, was investigated for its arsenic removal effectiveness from aqueous solutions under various conditions. Red mud efficiently removed As(III) between a pH range of 7.6 and 9; and As(V) in the pH range between 5.5 and 6. Pre-washing of the red mud with salt water considerably improved its arsenic adsorption capabilities. With appropriate red mud dosage, the residual arsenic in solution was decreased below the regulated acceptable arsenic limit (0.1 mg/L) from aqueous industrial wastes. The arsenic adsorption followed first-order rate kinetics and fitted the Langmuir isotherm model. Results suggest that red mud is potentially a useful adsorbent for removal of arsenic from contaminated water or industrial waste solutions.

Jan 1, 2003

By Wilfred Walker

With the advent of the New Global Tectonics a coherent pattern of geology is emerging. To the economic geologist this is of vital concern because the type of mineralization in particular environments is predictable. Developments in geological reasoning now take their place beside developments in geochemistry and geophysics. Much is known of the worldwide geography of the Alpine orogenic period because it is now ending its 200 million years of existence, starting with the Jurassic, and we can see the mid-ocean rises and the down flow zones, and between them the stable oceanic and continental platforms. The concepts of mantle cells, the spreading sea floor, and continental drift have gained general acceptance. The oceanographers have demonstrated the uprises like that in the mid-Atlantic. In this paper it is suggested that down flows in the oceans are marked by island arcs, like the West Indies; and down flows in the continents are marked by orogens like the American Cordillera. The number and position of mantle cells is controversial: a total of about 16 cells is suggested in this paper. Certain cells expand, and as they carry continents with them give rise to concepts of plate tectonics. Specific types of mineral deposits are associated with the uprises, oceanic and continental platforms, and down flows. The uprises are accompanied by the currently described Red Sea and Salton Sea deposits, the oceanic parts of the platform have the nodular deposits, and the continental platforms have the post-tectonic deposits. However, most economic metal deposits are associated with the down flow zones in which the stage of geosynclinal development controls the type of deposit: (1) In the initial development stage the simatic upper mantle may be tapped and give rise to the volcanogenic massive base metal sulfide deposits and to the ophiolite suite which characteristically carries nickel, chrome, and cupreous pyrite. (2) In the early geosynclinal stage sialic crust is driven down into the simatic magma of the upper mantle and basic to acidic differentiates give rise to stocks accompanied by skarn and hydrothermal deposits. (3) The intermediate stage of geosynclinal development gives rise to tin-tungsten, lithium, and beryllium deposits as the magma chamber rises above the level of the upper mantle and there is no simatic component. (4) The late stage is one of regenerated deposits. The porphyry deposits are not restricted to stages but only by the time of generation of acid magma. As the geosynclinal system dies, the mantle is again the source of magma, giving rise to gabbro and diabase dykes and sills: in this last, post-tectonic, continental platform environment are found the Mississippi Valley type lead-zinc deposits, the Blind River and Witwatersrand type of sedimentary uranium and gold deposits, and also Sudbury's nickel. The key relationship of major ore deposits generated by downflows is depicted herein on a framework of uprises, platforms, and downflows in the Alpine orogenic period. There is evidence for nine orogenic periods, of which the Alpine period is the latest, having taken place from 3500 million years ago to the present. Each period was characterized by its own worldwide mantle cell system and associated uprises, platforms, and down flows. The cycle of geosynclinal development, including corresponding cycles of mineralization, can be precisely defined in relation to each of these orogenic periods. The development of the Alpine orogenic period therefore can be used as a guide to the study of the earlier orogenic periods which comprise well known periods: Kenoran, Hudsonian, Grenville, and Paleozoic; and less well known: Konkian, Aulian, Belomorian, and Elsonian [(Table 1)]. Each name is used for the period as a whole, and not for the main orogenic event.

Jan 1, 1973

By Nicholas J. Grant, Italo S. Servi

SPECIAL polishing and etching techniques were developed during an investigation of the high temperature mechanical properties of high purity aluminum (99.995 pct Al).* Electrolytic polishing was done successfully in the following electrolyte: 5 ml perchloric acid (72 pct), and 95 ml glacial acetic acid. No special precautions need be taken during the preparation of the electrolyte since no appreciable heat of mixing is evolved. Although the electrolyte is not an explosive, it is recommended that Jacquet's safety rules' be followed during the polishing operation. A voltage of 25 to 60 v gives a good polish in about 2 min at room temperature after preparation on 3/0 metallographic paper. Most of the grain boundaries are visible under the microscope after polishing. Since the current is controlled essentially by the resistance of the bath, it is necessary to keep the anode-to-cathode distance as constant as possible. Accordingly, polishing of irregularly shaped pieces will be difficult. A cooling bath and a stirring system are advisable in order to keep the temperature of the bath uniform and constant. Coarse-grained samples can be macroetched in a few seconds by lowering the voltage below 10 v. This is done after electrolytic polishing, without removing the sample from the bath, Fig. 1. The specimen can be repolished in less than 1 min by raising the voltage above 25 v. The "galvanic etching" technique, which has been described elsewhere,' was found to be helpful not only for macroetching, but also for microetching coarse-grained specimens. In fact, the different orientations of adjacent grains provide good contrast at the grain boundaries, when the sample is observed under polarized light. If the specimen is only partially etched, Fig. 2a, the grain boundaries can be located without completely destroying the appearance of the surface of the specimen. The unetched surface appears black under polarized light. Excellent color contrast is obtained by using a "sensitive tint" plate in the optical system of the microscope. In this case, the unetched surface has a magenta color, while the etched part of the sample assumes different colors varying from green to brown, according to the orientation of the grains. Etch pits were produced on high purity aluminum by using the technique suggested by Lacombe and Beaujard." Good results also were obtained by substituting 70 pct nitric acid for the fuming nitric acid recommended. This gave an etching reagent of the following composition: 70 ml nitric acid (70 pct), 50 ml hydrochloric acid (37.5 pct), and 3 ml hydrofluoric acid (48 pct). An example of the results is shown in Fig- 2b. The outline of the etch pits is revealed sharply if the specimen is observed under polarized light, as shown in Fig. 2c. These metallographic techniques are not suitable for the examination of commercially pure (2s) aluminum. References 'P. A. Jacquet: Metal Finishing (Nov. 1949) 47, p. 62. 21. S. Servi: Metal Progress (1950) 58, p. 732. 3 P. Lacombe and L. Beaujard: Journal Inst. of Metals (1947) 74, p. 1._________________________

Jan 1, 1952

By Anna Sieminska-Lewandowska, Monika Mitew-Czajewska

"The construction of 6.3 km long central part of 2nd metro line in Warsaw was completed in September 2014 (7 stations - out of which three 25m deep stations - built using cut and cover method; two single-track tunnels constructed using four EPB TBMs as well as a short NATM section with soil freezing below the existing road tunnel). Central section of the 2nd metro line was opened to public after verification and testing in March 2015. Design and build tender for the extension of this line in East (three stations) and West direction (three stations) was announced with total length of running tunnels – approx. 5 km. Detailed description of a very complex geotechnical context, different construction methods, challenges encountered and solved during construction and finally lessons learnt on this interesting project are presented in the paper. DESCRITPTION OF THE PROJECT Introduction The very first concept plan of the metro system in Warsaw was designed several years after regaining independence by Poland in 1918. In 1929, following the geotechnical survey, design works begun, but the economic crisis of the 1930s stopped it. After a few years of break, in 1938 a coherent concept of the metro network was proposed to be implemented in phases over the next 35 years. In total, construction of 46 kilometers of metro, including 31 km of tunnels and 15 km on surface, was planned. Unfortunately, World War 2 made the implementation of those plans impossible. In the post-war period several metro designs were elaborated, but none except one was scheduled for implementation. Construction of the 1st, 23.1 km long, North-South line commenced in 1983 and finished in 2008 (Sieminska-Lewandowska et all. 2009). Nowadays, Warsaw covers the area of 517 km2 and, according to year 2014 statistical data, the city has much more than 1.7 million inhabitants. Only one operating metro line is not sufficient for such a populated city. Up-to-date metro plan, shown on Figure 1, includes also 30.5 km long 2nd metro line. It’s route is divided into four sections: Western Section with the length of approx. 9.2 km and 9 stations, Central Section with the length of 6.3 km and 7 stations, North-East Section with the length of 7.7 km and 6 stations, South-East Section with the length of 7.1 km and 6 stations. The construction of the central part of the 2nd metro line in Warsaw was completed in September 2014 and its operation started in March 2015. The paper focuses on challenges encountered and solved and lessons learnt during construction of the central part of the 2nd metro line in Warsaw."

Jan 1, 2016

By Elsa Olivetti, Randolph Kirchain, Gabrielle Gaustad

"As scrap usage increases, it is often necessary to “dilute” the melt with primary aluminum to ensure the finished product meets compositional specifications. Secondary raw materials, particularly postconsumer scraps, often include high levels of unwanted or “tramp” elements, such as iron and silicon in the case of aluminum. Recent literature on this issue cites several causes including inherent contamination during processing as well as ineffective segmentation at end-of-life. To address this accumulation problem, “upgrading” solutions have been developed including: dismantling of end-of-life products, spectrographic or magnetic sorting of shredded scrap, and “filtration” technologies that remove tramp elements in the melt. Although it is clear that upgrading strategies enable increased usage of scrap, it is not clear that they would be economic or efficient. This work presents a set of analytical methods, based on chance constrained optimization, to quantify the potential environmental and economic value of several scrap upgrading technologies.IntroductionAluminum recycling has a number of key environmental and economic benefits. Compared to other materials, aluminum production has one of the largest energy differences between primary and secondary production: 175 MJ/kg for primary compared to 10-20 MJ/kg for secondary[1]. With energy and cost savings in mind, many producers now have targets of increasing their usage of secondary materials[2, 3]. However, the accumulation of impurities in these recycled material streams provides a significant compositional barrier to these goals[4].A growing number of studies and literature would suggest that accumulation of unwanted elements is a growing problem, in all recycled material streams. In the case of aluminum, the list of problematic impurities is quite large, including but not limited to: Si[5, 6], Mg, Ni, Zn, Pb, Cr[7], Fe[5-7], Cu[6, 7], V, and Mn[6]. Metals recycling is a metallurgical process and is therefore governed by the laws of thermodynamics. The removal of unwanted elements in the scrap stream is dictated by the energy considerations of the melt process. Compared to many metals, aluminum has a high degree of difficulty in the removal of tramp elements, due to thermodynamic barriers. Therefore, with no simple thermodynamic solution, producers must identify strategies through-out the production process to mitigate this elemental accumulation."

Jan 1, 2008

By M. K. Gangal, A. E. Hall, S. B. V. Stewart

"An investigation into the problem of atmospheric fog in Canadian mines is described. Fog occurs in several mines and the reduced visibility can result in the closure of workings for safety reasons. Information on the mechanisms of fog formation are discussed and the methods for improving conditions are reviewed with their relative costs.INTRODUCTIONAtmospheric fog occurs in several Canadian mines during spring and summer. The fog which reduces visibility, contributes to loss of production and increased accident risk . Closure of ramps in mechanized mines causes mining to be stopped or rescheduled, and stoping and grade control may be affected . Increased corrosion of equipment may result from acidic fog .Fog is commonly caused by saturated air being compressed and heated by an inlet fan and then being circulated in an ascensional system with heat transfer to the walls of wet airways. This causes supersaturation and water droplets condense to create fog, with liquid water contents of 0.5 g/kg to 3 g/kg of air. These concentrations reduce visibility to less than 10m and prevent mining. Less severe fog is usually tolerated as a nuisance, about which little can be done."

Jan 1, 1989

By C. Fiore

The annual general meeting of the branch was held in the Witbank Golf Club on Thursday, 28th August, 1969 at 5:00 p.m.

Nov 1, 1969

By Lynn Salvati, Colin LaVassar, Loic Galisson, Joel Theodore, Lynette Sla

"Sound Transit’s University Link and Northgate Link projects will add 6.75 miles (10.9 km) of twin-bored tunnel to Seattle’s light rail system, extending the route north from downtown Seattle. The tunnels are being constructed primarily in glacial soils using pressurized-face tunnel boring machines. Cover over the tunnel alignment varied from 13 feet to over 300 feet (4–91 m). Since the tunnels are located in densely populated urban areas, controlling ground movements and monitoring settlement were essential to success of these projects. Hundreds of geotechnical instruments, including extensometers, surface settlement points, and near-surface settlement points, were used in both projects to monitor settlement. The observed data were compared to settlement predictions made prior to tunneling, and analyses performed to update empirical factors to better estimate settlements. Recommendations for designing efficient and cost-effective settlement monitoring programs are provided based on the review of the monitoring data and analyses.INTRODUCTIONThe paper includes data from Sound Transit’s University Link and Northgate Link projects. These projects will add 6.75 miles of twin-bored tunnel to Seattle’s light rail system. The tunneling for University Link will extend the light rail system from downtown Seattle to the University of Washington. Tunneling from downtown Seattle to the Capitol Hill Station was completed under the U230 contract, and tunneling from the Capitol Hill Station to the University of Washington Station was completed under the U220 contract. The Northgate Link extension will extend the light rail line north of the University of Washington, including approximately 3.5 miles (5.6 km) of twin tunnels between the University of Washington Station and the Maple Leaf Portal and two stations, U District Station and Roosevelt Station. Tunneling for the Northgate Link project is still underway as part of the N125 project. At the time of writing, tunneling from the Maple Leaf Portal to Roosevelt Station has been completed. Therefore data labeled as N125 in this paper only include the portion of the alignment from the Maple Leaf Portal to Roosevelt Station."

Jan 1, 2016

By S. B. Keith

Cerro de Pasco Corporation operates five large base metal mines in Peru having a combined production of some three million tons of ore a year. An integrated complex of concentrators, smelters and refineries produces annually about 25,600 short tons of copper, 48,100 short tons of lead, 60,500 short tons of zinc metal, 102,300 short tons of zinc concentrate, 8,272,000 ounces of silver and substantial amounts of bismuth, cadmium and selenium. Geology plays an important role in these operations. The organization of detail geologic work in and around the Cerro mines was set up by John M. Boutwell in 1918 and a geology department was established in 1920. Growing through the years, the department technical staff now numbers over thirty men and. their work covers all phases of geological investigations. Many outstanding geologists of the past and present, too numerous to name here, have studied and contributed to the knowledge of the deposits and the ever growing list of Cerro "alumni" must rival that of any other mining organization. Numerous papers on the geology of Cerro's mines can be found in the technical literature and several doctoral theses have been presented on Cerro subjects as indicated in the attached bibliography, Specimens of Cerro's ores can be found in museum, college and university collections throughout the world. Yet, as with all mines and mining districts, the geologic knowledge of Cerro's deposits in Peru is being revised and added to constantly. This presentation cannot hope to cover adequately all the phases of the geology and mineralization. For a more complete background and discussion of the mine you are referred to the bibliography. Here I shall outline only briefly the more important geologic features and describe some of the newer developments of recent years The credit for the data presented here belongs to the many geologists who have worked or are now working for Cerro de Pasco Corporation, but I must assume sole responsibility for any omissions or variations in the interpretation of their work.

Jan 1, 1965

By J. W. Leonard

This expanded and more detailed supplement to earlier published work1 is offered as a means to demonstrate the high empirical correlation which exists between the readily measured coal bench scale test parameters of volatile matter (d & a.f.), Hard-grove grindability index (HGI), Koppers cone bulk density (BD) and pulverization level (% passing a 1/8-in. screen) to the less readily measured full scale coke stability index. Thus, Fig. 1, 2 and 3 represent the correlated test data contained in Tables I, II and III respectively. Ninety-six coals are correlated so that 97% of the resultant cokes fall within two points and 100% fall within three points of the actual tested coke stability indices. The main generalizations which can be drawn from the correlation of these coals are as follows: 1) The coke stability indices for higher bulk density coals (46.0 BD to 50.6 BD) appear to be largely influenced by differing combinations of factors for coals above and below a pivotal point of approximately 36% to 37% volatile matter. Below this pivotal volatile matter coke stability index appears to be influenced largely as a result of changes to the coal volatile matter and pulverization level. While above this pivotal volatile matter coke stability indices appear to be dependent on the coal hardness, as measured by the HGI, and to some extent upon coal volatile matter. Pulverization appears to have little influence on the coke stabilities of the harder coals (52 HGI to 58 HGI) of greater than 36% to 37% volatile matter. 2) The coke stability indices for lower bulk density coals (41 BD to 45.9 BD) appears to be largely influenced by changes to coal volatile matter and pulverization level for softer coals above approximately 58 HGI. 3) The main empirical observation to be drawn from these results is that for coals above approximately 36% to 37% volatile matter the quantities of hard and soft constituents as measured by the HGI are important when defining coal rank for correlation to the coke stability index.

Jan 1, 1965

With the ever increasing problems of narrowing profit margins, and increased liability, a solution/option to SEE members is needed. It is essential that all members understand the benefits of utilizing explosives in combination with other methods of achieving the required result on difficult rock or concrete removal projects.

Jan 1, 1995

By H. I. Smith

THE recently developed potash industry in southeastern New Mexico, though based on a relatively new discovery, marks the latest and perhaps culminating phase of the effort to obtain a domestic source of potash that began with the leaching of wood ashes more than 300 years ago. In the search for mineral potash in America, the Geological Survey has played a conspicuous part and has paved the way for much of the private activity that now bids fair to free the nation of foreign domina¬tion in supplying the nation's potash requirements. HISTORICAL REVIEW A pamphlet published by Thomas Stephen in 1758 pictures the industry in its early struggling condition.1 Just before the Civil War, a deposit of mineral potash had been found in Germany and its value as a fertilizer had been discovered. On this account and because the supply of wood ashes had decreased, the Ameri-can potash industry gradually lost its importance. During the next 50 years, with European potash available with little effort and with satisfactory substitutes on the market for the manufacture of soap, the interest of the American people in American potash declined. In 1910 this interest was suddenly revived by the abrogation of American potash contracts in Europe. Congress passed an act, approved by President Taft March 4, 1911, providing for "researches with a view to determining geological conditions favorable to the presence of deposits of potash salts." Appropriations were made to the Geological Survey and the Bureau of Soils to carry out the provisions of this act. The work of the Survey was directed toward the finding of commercial bodies of natural soluble potash salts; the Bureau of Soils was more concerned with the processes of extracting potash from industrial wastes and organic sources. Private agencies also became interested in the program. The Geological Survey has continued its search throughout the ensuing period of more than 20 years and has studied many types of deposits in many parts of the country.

Jan 1, 1933