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By S. Norman Kesten

The Galena mine is located astride the Polaris fault in the Coeur d'Alene district of northern Idaho. The surface installations are about a mile up Lake Gulch, the mouth of which is about 2.4 km (1 112 miles) west of the old town of Wallace. The mine had its beginnings when the first claims were located in the early boom days of the district in the 1880s and when the first underground ore bodies were opened up in 1917. During the ensuing 14 years, ore was mined from which were recovered 5.4 Mkg (12 million lb) of lead and almost 14.2 Mg (112 million oz) of silver. Workings consisted principally of a vertical shaft from surface to the 800 level and an offset underground shaft to the 1600 level, together with extensive lateral openings. High-grade silver-copper ore was discovered near the Silver Standard fault in the Sunshine mine, a few miles to the west, on the 1700 level in 1930. By 1937, the Sunshine and adjacent mines were producing silver-copper ore on a regular basis. In 1943 additional ore of a similar type was found along the Chester fault, to the east of the principal Sunshine workings. The interest of American Smelting and Refining Co. (renamed ASARCO in 1975) was aroused and the company's geologists determined that the Galena mine, idle since 1931, provided a geological environment in which similar ore might be found. After negotiations were initiated with the owners of the property, Callahan Zinc-Lead Co., the property in question was deeded to Callahan's wholly owned subsidiary, Vulcan Silver-Lead.

Jan 1, 1990

By Honggang Zhong, Xin Cao, Qijie Zhai, Hongmei Song, Congsen Wu, Cheng Zhang, Jingzheng Ye

"The influence of superheat on the solidification structure and ferrite/austenite phase transformation of a novel lean duplex stainless steel (DSS) was investigated on a setup, which designed to thermally simulate the continuous casting process. The results showed that the macrostructure of the samples all exhibited chill zone, columnar zone and equiaxed zone. The distance from chill zone to position of columnar to equiaxed transition (CET) moved from 51.0 mm to 39.8 mm with an decrease of superheat from 70 °C to 10 °C, and that the grains in the chill zone tended to be finer. In equiaxed zone, the fme and uniform grains were observed when superheat higher than 40 °C; while, coarse grains were found in samples poured at low superheat. Generally, the volume fraction of ferrite increased along the dendritic growth direction, and stabilized in equiaxed zone. The high superheat decreased the volume fraction of ferrite in equiaxed zone, while it had indistinctive influence on chill zone and columnar zone.IntroductionDuplex stainless steel with approximately equal volume of ferrite and austenite, offering an attractive combination of corrosion resistance and mechanical properties. [ l]. The production of DSS, worldwide application in structural engineering[2] and petrochemical industry[3], have increase by more than 100% in the latest decade[4]. But due to the sharp prices increase of nickel and chromium, lean duplex stainless steels which have lower contents of alloy elements were developed. They perform well in both mechanical and corrosion resistance[S, 6] and even have TRlP(Transformation Induced Plasticity) effect[?]. Nonetheless , the mechanical properties of DSS was affected greatly by the solidification structure, such as columnar to equiaxed transition (CET), grain size and phase content[8]. So, the solidification behavior of stainless steel was investigated widely"

Jan 1, 2014

By Robert F. Mehl

THE purpose of a symposium, I take it, is to gather together a group interested in a common intellectual field, in order to exchange views, and to appraise the state of knowledge. Symposia are the more successful, the greater the activity in the chosen field and the wider the range of applicability of the information gained. From time to time, as emphasis changes from one field of research to another, a given subject may enjoy popularity and later retire into a scientific somnolence, for fashions change even among engineers and scientists. The subject of this symposium, however, enjoys the advantages of wide applicability and of high current interest and productivity in results. It is a timely subject for a symposium; with much new information, surely metallurgical engineers should now devote an increasing attention to its application to practice. In beginning the symposium, I shall attempt briefly to appraise our basic knowledge in the field, to survey instances of practical usefulness, and to suggest where new work might be most productive of useful results. There are many examples of direct practical application of diffusion knowledge, and it is the purpose of the several papers in this symposium to review these. In this introduction I shall attempt to take a broad view, which, while it will but poorly serve the engineer in the solution of any given problem, may perhaps be of some use in assessing the state of knowledge in this field. RATE OF DIFFUSION Liquid Metals The process of diffusion among liquid metals, of gases in liquid or solid metals, or among solid metals, is ubiquitous, to say the least. The manufacture of alloys by the intermelting of metals, the addition of ferroalloys to molten steel, the deoxidation of molten alloys, all involve diffusion in the liquid state. The oxidation of molten copper for purposes of purification, the unsought oxidation of alloys generally during melting and casting, the reaction of liquid steel with oxidizing slags in the open-hearth furnace, the absorption of nitrogen by liquid steel, particularly in the bessemer furnace, all operate by the diffusion of gases in liquid metals. These processes have not been studied much from the viewpoint of rates of diffusion. Alloys are made by melting metals with stirring and with allowance of time for mixing (which is diffusion) but I know of no studies that seem to define the necessary times, and though in only very rare cases can faulty properties of the finished castings be ascribed to inadequate mixing, and though certainly in most cases, with stirring, the rate of diffusion is adequate to give sufficient mixing, a more quantitative treatment would be good to have. It is not wholly certain that thorough and sufficient mixing is at all times attained, for I suspect that ferroalloy additions to steel, and that additions of aluminum to steel as a deoxidizer, especially in the sampling of steels

Jan 1, 1944

By James P. Savely

This paper describes the development of a trim blast design to improve the stability of a final pit wall. Description is given of the effects of rock characteristics, rock type, and pit plans on the blast design. Currently, six benches have been mined with trim blasting. A more stable final wall has resulted and the successful program has reduced mining costs over an extended time period. Low cost blast monitoring and field observation were used to determine peak particle velocity and blast damage. Using criteria developed from this relationship, trim blasts were designed and evaluated.

Jan 1, 1986

By B Banerjee, N Kumar, S Parihar

Rampura Agucha Pb-Zn Mine (RAM) is located about 200 km to the south-west of Jaipur in the state of Rajasthan, India. Open pit mining operations commenced in 1988 and continued to 2018. RAM open pit footprint is the largest in India with length of 2000 m, width 1500 m and depth of 400 m. Development of an underground mine under the operating pit commenced in 2013, through trial mining longhole open stoping with cemented backfill was established as a preferred mining method. Nine years in operations underground mine has reached the production capacity of 4.5 MT, which represent more than 70 per cent of the ore volume mined by the pit. RAM is currently the world second largest underground Pb-Zn mine.

Nov 29, 2022

By C. J. Li, J. L. Feng

In the present study we focuses on developing the poroelasticity model that deals with adsorptioninduced permeability change mostly occurred in porous media constituted several phases such as coal. The underlying pressure induced by adsorption is obtained by Virial expansion form, which is substantially founded on statistical physics. The corresponding thermodynamic pressure applying on the pore surface is then used to detail the pore pressure and further to evaluate the macroscopic volumetric strain and the porosity. In the process of physical adsorption, the adsorbed phase is in thermodynamic equilibrium with the gas phase regardless of pore size, and the corresponding chemical potentials are all equal. The relationship between surface strain and volumetric strain is derived under infinitesimal deformation conditions to gain an explicit formulation of pore surface area with respect to volumetric strain and porosity. After the formulation of surface stress modified by the Langmuir isothermal adsorption is derived, the differential micromechanical constitutive equations of porous media are obtained. By supposing that the ratio of current permeability to initial is equal to the cubic ratio of current porosity to initial porosity, the differential equations for permeability change is consequently derived. The numerical simulations by the present model for permeability change of coal induced by adsorption of CO2 and CH4, respectively, are presented under confined stress conditions. The predictions from the model are good in agreement with the experimental data of sorption-induced permeability change of coals in the literature.

Jan 1, 2015

By S. C. O?Brien

This paper develops the procedure for simulating the special locked-cycle Work Index laboratory test using the kinetic parameters obtained by conducting standard size-mass balance (SMB) grinding tests and presents the results for three materials - quartz, a taconite iron ore and a bituminous coal. It was found that the WI could be determined by simulation; however, if a material breaks abnormally, a full description of its abnormal breakage is necessary. It was also found that the sensitivity of the WI test procedure to the sieving process and the estimating of the 80% passing size of the sieve undersize is sufficient to question the practice of quoting a WI to two or more decimal places. Finally, if a material grinds abnormally in the Work Index mill, then the WI test should not be conducted.

Jan 1, 1987

By Gary L. Seider, Dana A. Wesolek, Fred C. Schmednecht

"A new condominium project, The Atelier, developed by Pickus Companies located at the corner of Bryn Mawr and Sheridan in Chicago, IL required an earth retention system to protect the surrounding roads, alley, and existing neighboring apartment bui lding during its construction. Slurry Systems, Inc. (SSI) and Ground Engineering Consultants, Inc. designed the earth retention system using cantilevered sheet piling for three of the four sides: two sides bordering major streets and one side bordering an alley. For the fourth side, which borders an existing occupied brick building, a combination of sheet pil ing and AB. CHANCE® helical screw piers were used. SSI was actively involved in the review process of its earth retention system with the City of Chicago and quickly learned that there was no specific code for hel ical piers/anchors. (It appears that this is the case with most metropolitan cities throughout the United States). Consequently, the approval of underpinning for this project became the critical path, as much testing, calculations, meetings, and other details were required prior to its approval.SSI and AB. CHANCE® recognized that this process for underpinning approval must be seen by other contractors/suppliers who wish to use helical piers/anchors in the City of Chicago. Consequently, this project served as an opportunity to work with the City of Chicago and the City's Building Code Committee in furthering the development of the Helical Piers/Anchors Code, Section 1814. INTRODUCTION - HELICAL PIERSDefinition. A helical pier or anchor consists of one or more helix-shaped steel bearing plate(s) attached to a central steel stem (solid bar or pipe), which is installed by rotating or ""torquing"" into the ground. Each helix is attached near the tip, is circular in plan , and is formed into a screw thread with a defined pitch. Helical piers/anchors are pre-fabricated and can derive their load-carrying capacity through both end bearing and skin friction. The helical piers/anchors can be augmented with grout."

Jan 1, 2005

By Michael D. Balen

During the years 1987 through 1989, the Bureau of Mines Alaska Field Operations Center (Bureau) in cooperation with the Western Field Operations Center and the Alaska Division of Geological and Geophysical Surveys (ADGGS), conducted mining, geological, and geochemical investigations in the 5.7 million-acre Valdez Creek Mining District (VCMD). This investigation was conducted as part of the Bureau's continuing Mineral Land Assessment (MLA) mining district studies program. The Bureau's MLA program is designed to provide reliable and comprehensive mineral resource information that supports mineral resource policy and land use decisions made by Congress and Federal land management agencies. The information also provides the basis for decisions that would expand the domestic supply of important mineral resources, primarily strategic and critical minerals. Much of the MLA work is done jointly with cooperating State or U.S. geological surveys.

Jan 1, 1992

By A. W. Newberry

The Virginia copper district is situated in North Carolina and Virginia. It contains many mines and prospects that were active at the turn of the nineteenth century. The Bureau of Mines, as part of the strategic-minerals program, began a project in September 1942 to investigate and explore the most promising of the mines in the district. The Seaboard, High Hill, Durgy, and Blue Wing mines were the sites of the main project activity. This report deals principally with these four mines. Drilling did not discover any new ore shoots but indicated the persistence of known ore shoots in depth. There appears to be no indication of impoverishment of copper with depth.

Jan 1, 1948

By Hsun Hu, R. S. Cline

The effect of rate of deformation on texture formatiotz has been studied with cube-oriented single crystals of 3 pct Si-Fe, compressed 80 pct at two widely different rates. Compression at a low rate (crosshead speed, 0.1 ipm) produces large orienta-tional changes and coarse deformation bands, whereas little change in orientation is observed, particularly at the surface of the crystal, when compressed at a high rate (impact velocity, -500 ips). Thin plates of mechanical twins are produced at the high rate, but their contribution to the deformation texture is practically negligible. The crystal deformed at a high rate has a lower hardness and a more uniform dislocation structure and is morc resistant to recrystallization. There is also a dilference in the recrystallization texture between the slowly and rapidly compressed crystals. These results indicate that plastic flow is less "turbulent" at high strain rates than at low strain ratcs. THE behavior of metals under high-speed deformation has been the subject of wide study in the past decade. Most of these works were concerned with mechanical properties during testing at high rates of loading, the resulting structures, and the theoretical aspects of the observed phenomena. The present status of knowledge and research activities in this field has been documented in recent publications.17' There is, however, very little information available in the literature concerning the effect of high-speed deformation on the texture formation in metals. The possibility of an effect of rate of deformation on texture is suggested by the microstructural differences observed between normally and very rapidly deformed samples. Aside from the strong tendency for twinning (and phase transformation in certain metals) in high-speed deformation, the slip-line patterns and the dislocation configurations show marked differences as a result of large differences in the strain rates. For instance, in mild steel in static and dynamic compression, Campbell and co-worker3,4 observed that coarse slip occurred on several systems in specimens deformed at normal strain rates, whereas specimens deformed rapidly showed only fine slip on fewer systems, the slip-line pattern being very similar to that in specimens deformed at low temperatures and at normal strain rates. The absence of multiple slip was also noticed by Dieter5 in shock-loaded nickel. The dislocation configuration in an iron shock loaded at 70 kbar pressure was shown by Leslie et al.6 to be similar to that produced by light rolling at low temperature—the dislocation lines were mostly straight and uniformly distributed. These observations suggest that the mode of deformation at high strain rates is notably different from that at low strain rates. Consequently, the nature and the extent of lattice reori-entation during deformation should also be different. This investigation was undertaken to test this idea. MATERIAL AND METHOD The remaining part of a single-crystal ingot of a 3 pct Si-Fe alloy,* prepared for an earlier investi- gation,1 was used in the present studies. Specimens 9/16 in. square and 0.365 in. thick were cut from this ingot with (001) planes parallel to the square surfaces, and the [loo] and 1010] directions parallel to the edges of the specimen, within ±1 deg. These machined crystals were etched to remove distorted metal, and annealed at 1300°C for 24 hr in a purified helium atmosphere. The annealed crystals had a hardness of 161 Dph. The crystal orientation was rechecked with X-ray back-reflection techniques. In high-strain rate experiments the crystal was compressed in a Dynapak machine to approximately 80 pct reduction in thickness (from 0.360 to 0.070 in. with an impact velocity of -500 ips). Thus, the duration of loading was approximately 6x 10-4 sec, and the average strain rate was about 103 sec-1. As a result of this rapid, severe deformation, the specimen became a roughly circular thin disc. The original shape of the crystal, however, could still be recognized by a diffusely outlined square area in the center of the disc. For compression at a low speed, the crystal was deformed in a universal testing machine at a rate of crosshead movement of 0.1 ipm. Compared with

Jan 1, 1965

Brunswick Mining and Smelting Corporation Limited operates a large base metal property near Bathurst, New Brunswick in eastern Canada. Nominal capacity for the underground mining operation and concentrator is 10 250 DMT/day. Four concentrates are produced by differential flotation technology to recover minerals containing copper, lead, zinc and silver. Two characteristics of the Brunswick ores have a major impact on mineral processing operations. The mineralogy of the ore is complex with a total sulphide mineral content of 85 per cent. In addition, the ore is extremely fine-grained, and satisfactory liberation is difficult to achieve. These characteristics directly influence flotation selectivity and thereby affect metallurgical performance. Significant improvements in metallurgical performance have been achieved through the application of basic grinding and flotation principles using conventional milling equipment. Current operating practice and the metallurgical advancements are detailed.

Jan 1, 1993

By Dezhong Kong, Jaichen Wang, Shengli Yang

"The stability control of longwall coal face is the key technology of large-cutting-height mining method. Therefore, a systematic study of the factors that affect coal face stability and its control technology is required in the development of large-cutting-height mining method in China. After the practical field observation and years of study, it was found that the more than 95% of failure in coal face are shear failure. The shear failure analysis model of coal face has been established, that can perform systematic study among factors such as mining height, coal mass strength, roof load, support resistance, and face flipper protecting plate horizontal force. Meanwhile, sensitivity analysis of factors influencing coal face stability showed that improving support capacity, cohesion of coal mass and decreasing roof load of coal face are the key to improve coal face stability. Numerical simulation of the factors affecting coal face stability has been performed using UDEC software and the results are consistent with the theoretical analysis. The coal face reinforcement technology of largecutting- height mining method using the grouting combined with coir rope is presented. Laboratory tests have been carried out to verify its reinforcement effect and practical application has been implemented in several coal mines with good results. It has now become the main technology to reduce longwall coal face failure of large-cutting-height mining method.INTRODUCTIONLarge-cutting-height mining method of more than 3.5m mining height, is one of the main methods for thick-seam mining in China. Currently, the largest mining height is 7.3m and the support capacity is 1,800mt. Shendong and Jincheng mining area have the best use of large-cutting-height mining technology (Wang, 2009). Generally, the mining height ranges from 6.5m to 7m and the support capacity ranges from 1,000mt to 2,000mt, annual output of the panel is between 10 and 12 million tons and the highest are 15 million tons. The main goal of large-cutting-height mining technology is to achieve high yield and high efficiency by increasing the advancing speed of longwall face (Yuan, 2011- 2012). However, in certain geologic conditions, rib spalling and roof falls in the unsupported area often occur. Because of the large tonnage of large-cutting-height mining equipment, once the rib spalling and roof falls cause the equipment to be out of alignment, the face advancing speed could be affected seriously that in turn affects the output (Yang, 2012). Therefore, studying the failure mechanism and control technique of coal face in large-cuttingheight mining method is of great significance."

Jan 1, 2015

By Tamas Kekesi

Anion exchange in HCl media is considered an efficient alternative to the combination of the conventional purification methods. Anion-exchange distribution functions have been determined for cobalt and the main impurity elements by the technique of batch equilibration. Results were confirmed by spectrophotometric investigations and elution tests. Based on the new and the available distribution functions, combined with the assessment of thermodynamic stability, a procedure of anion exchange separation has been devised to eliminate virtually all the impurities from the cobalt-chloride solution. Separation of copper has been enhanced by the introduction of a preliminary step under reduced conditions. The rest of the impurities are eliminated in a second anion-exchange step applying rinsing and elution stages under oxidized conditions. The optimum parameters of the procedure have been determined according to performance characteristics (purification ratios, yields and volume efficiencies) derived from the analysis of elution curves obtained with laboratory scale ion-exchange columns. Special computer programs have been developed to facilitate thermodynamic simulation, analytical correction and data processing.

Jan 1, 2003

By S. Terry, J. G. Munro

A unique feature of the recently dedicated pelletizing complex of Hamersley Iron Pty. Ltd. is the dry grinding circuit for the iron ore fines. This facility, located at Dampier, some 800 miles north of Perth, Western Australia, has a rated annual capacity of 2 million tpy of iron ore pellets. The Mt. Tom Price orebody, which supplies the pelletizing plant, is a massive deposit of high-grade hematite containing an estimated 500 million tons of ore averaging 64% iron. The main impurities are ferruginous shales that occur in bands of varying widths in the orebody. An average analysis shows 4.4% SiO2, 2.0% A12O3, 0.05% P and 1.8% LOI.

Jan 5, 1968

By S. J. Oosthuizen

This paper examines innovation in relation to the availability of anew material: the metal titanium. The paper aims to highlight the need for the inclusion of entrepreneurial innovation as a necessary focus area in the development of a titanium metal value chain. Both the Department of Science and Technology (DST) and the Department of Mineral Resources (DMR) have identified the creation of titanium metals production capabilities as a key growth area for South Africa. Using historical literature as a source of data, the activities of selected innovators who used titanium metal as a central component in their success, were investigated. The origin of the process innovation behind the titanium metals industry, and two titanium product innovations: namely, medical implants and sporting goods, were detailed as case studies. It was found that individual innovators were responsible for the creation, and rapid growth, of the titanium industry and titanium product applications. There is a need to link the current research and development into titanium metals production with individuals and organizations capable of commercializing innovative processes and products.

Jan 1, 2011

By Gene Asai

The Bureau of Mines investigated the caustic extraction of alumina and soda from retorted dawsonite-bearing oil shale, as part of a program to devise technology for treating alternative domestic sources of alumina for the production of aluminum metal. Colorado oil shale yielding 13 pct oil (35 gal/ton) and containing 12 wt-pct dawsonite (representing about 4 pct extractable alumina) was retorted to obtain oil-free (spent) shale Spent shale was leached with dilute NaOH to determine the effect of particle size, retorting temperature, leaching variables, and storage conditions on extraction of alumina and soda and dissolution of impurities. Maximum alumina and soda extractions were obtained by promptly leaching minus 28-mesh spent shale, obtained by retorting raw shale at about 5000 C, with 0.5N NaOH. Under these conditions, dissolution of impurities such as Ca, Fe, Ti, and P was low. Leaching tests were made on spent shale stored for periods of up to 30 days at 0° to 42° C and at 0 to 100 pct relative humidity (RH). These tests indicated that significant reductions in alumina extraction would occur if spent shale were stored in ambient Colorado air under naturally fluctuating temperature and humidity.

Jan 1, 1983

By B. D. Cullity, O. P. Puri

The magnetostrictia of nickel after increasing amounts of plastic elongation was measured at field strengths up to 1500 oe. In addition, the residual stress was measured by means of X-ray line shifts. The observed decrease in magnetostriction following plastic strain is shown to be associated with residual compressive stress. If a metal bar, whose longitudinal axis is taken as the x direction, is plastically elongated in the x direction and then unloaded, X-ray diffraction measurements will indicate the presence of a residual compressive macrostress 0%. However, stress measurement by means of mechanical relaxation does not reveal any macrostress. In a previous paper1 the fictitious macrostress indicated by X-rays was ascribed to a particular distribution of micro-stress, namely, one in which the bulk of the material was stressed more or less uniformly in compression and a very small portion in tension. It was shown that this distribution would account for Neurath's measurements2 of magnetic losses in silicon steel, because of the effect of residual stress on magnetostriction. The present paper is concerned directly with magnetostriction, in nickel, and with the effect on magnetostriction of the residual stress created by plastic elongation. The residual stress was determined by measurements of X-ray line shifts. MATERIAL AND METHODS Commercially pure "A" nickel was investigated. Its nominal composition, in weight percent, is 99.4 Ni + Co, 0.2 Mn, 0.15 Fe, 0.1 Cu, 0.1 C, 0.05 Si, and 0.005 S. Magnetostriction was measured by means of SR-4 electrical-resistance strain gages mounted on specimens 1/4 in. sq and 8 in. long. Magnetic fields up to about 1500 ce were provided by a multilayer, non-cooled solenoid. A considerable amount of heat was developed at the higher field strengths, and, to avoid errors due to changes in the specimen temperature, the following procedure was adopted. Each measurement of the magnetostriction X at a particular field strength H was preceded by demagnetization and an adjustment of the strain indicator to zero; the field H was then quickly switched on and the strain read immediately. Curves of ? vs H were flat for field strengths above about 750 oe for all specimens, and this constant value of X was accordingly taken as the saturation magnetostriction ?s The X-ray measurements of residual stress were made with a Norelco diffractometer on specimens cut from flat bars 1 1/4 in. wide, 1/8 in. thick, and 12 in. long. These measurements were confined to lattice planes parallel to the surface of the specimen. Two reflections were studied: the 311 CrKß line at 28 = 157 deg, and the 420 CuKal line at 28 = 155 deg. The line centers were determined by fitting a parabola to the peak of the line, as suggested by Ogilvie3 and as modified by Koistinen and Marburger.4 The CuKa doublet from the plastically elongated specimens was first resolved by the Rachinger method5. All X-ray measurements were made by counting at fixed angular positions. RESULTS The results of the magnetostriction measurements are shown in Fig. 1 and Table 1. The magnitude of

Jan 1, 1963

By J. L. Holman

The Bureau of Mines is conducting research to recover strategic and critical metals such as Ni, Co, and Cr from mixed contaminated super-alloy scrap. One approach being studied involves melt refining of superalloy scrap to produce anodes for electrolytic deposition of Ni-Co alloy. This melt refining of superalloy turnings is described based on melt-oxidation and oxidation-carburization experiments, using roasted superalloy grinding sludge to supply the 0 needed to oxidize Cr and other readily oxidized elements to the slag. Controlled melt-carburization subsequent to oxidation improved the metal phase recovery of Ni and Co to well over 90 pct and decreased electrolytic solubility of Cr, Mo, and W by carbide formation. Electrolytic refining experiments were conducted using a controlled-potential mode (preset cathode potential). Data show effects of Fe and Cr impurities, cation concentration, electrolyte pH, S04-Cl electrolyte ratio, temperature, cathode potential, and cation-selective membrane use on current efficiency, current density, and deposit composition. Disposition of Ni, Co, Cr, MO, W, and Fe is compared for melt-oxidized versus oxidized-plus-carburized anodes. Deposits containing >97 pct Ni + Co (major impurity Fe) have been routinely obtained from scrap anodes. Research is continuing to improve deposit quality in sustained deposition and to recover Cr and other metals from refining slags and anode sludges.

Jan 1, 1986

By Lyle W. Talbotr

The DeLamar Silver Mine is a Joint Venture between Earth Resources Company, the Canadian Superior Mining Company and the Superior Oil Company. The property is a consolidation of several old operations in the district. The more widely known are the DeLamar and Sommercamp Mines. The location is 20 miles northeast of Jordan Valley, Oregon and 55 miles southwest of Boise, Idaho. The mine is on the south slope of DeLamar Mountain in the Owyhee Mountains of southwest Idaho Initial interest started in 1969 with serious exploration beginning in 1970. The feasibility study was completed in 1974, and in 1975 Mountain States Engineers were retained to design and build the plant. Processing of ore began in March of 1977 with the first bullion poured in April of that year. The plant is currently processing some 2200 TPD of ore with a grade of four ounces of silver and 0.03 oz. of gold per ton of ore. Cyanide consumption is 2.5 lb/ton, zinc consumption of 0.3 lb/ton and flocculent consumption of 0.5 lb/ton. A flowsheet is shown as Figure I. The grinding circuit is of two stage design. The primary mill is an 18 ft. dia. by 9 ft. long semi-autogenous unit. The secondary mill is a 9 1/2 ft. dia. by 15 ft. long overflow ball mill. The mill discharges are combined and sent to 15 in. cyclones for classification. Cyclone overflow reports to leaching with the underflows reporting to the ball mill. The cyclone feed pump is an 8X6 metal case pump. The primary mill has 1000 installed horsepower and rotates at 68% of critical speed. The ball mill has 700 installed horsepower and rotates at 72% of critical speed. Because the primary mill is horsepower limited the ball charge is varied to maintain the desired throughput. The mill power is held at 980-990 HP by modifying the feed rate. Four inch forged steel balls are added any time the ore feed fails to reach 100 tons per hour for four hours. During periods of extremely hard ore, the ball charge has been as high as 14 v/o and at other times the mill has operated fully autogenous for weeks.

Jan 1, 1980