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By D. M. Hausen

A refractory siliceous low-grade silver ore (265 g/t Ag) from a prospect in Sonora, Mexico was investigated mineralogically and metallurgically to evaluate extraction of the silver by conventional methods. Approximately half of the silver was recoverable, occurring as coarsely crystalline acanthite (70-300 Am) that was liberated in material crushed to minus 10 mesh. The remaining silver is refractory and occurs mostly as finely locked (-2 to 0.2 Am) acanthite in cherty quartz, and as minor amounts of finely disseminated stylotypite or freibergite in fluorite. The mineralogic data have thus served to explain the 50-60% recovery of silver by flotation and cyanidation.

Jan 1, 1991

By Zhiqian Zhang, Chao Wu, Chao Li, Hongxu Li, Chuanqi Jiao

"Many used electronic and optical products contain cerium of rare earth oxides, but it is difficult to recover such rare earth compounds by traditional metallurgy methods. The proposed supercritical water metallurgy is a novel way, perhaps it will be very helpful for rare element recycling, but the thermodynamic properties at such special systems is not clear. In the paper the H20-CeO-CeO2 and H2O-CeO2-Ce2O3 ternary system phase diagram were produced under the pressure of30MPa with different temperature of350°C, 375°C and 400°C. The stability existing area of possible cerium compounds and different ions like Ce2+,Ce3+,Ce4+,W,HO2-,0ff ,CeOH2+,CeO+ and CeO2· were determined.IntroductionCerium is an extensively used metal element playing an important role in the rare earth elements. CeO2 is an apparently simple binary oxide with cubic fluorite structure [l]. Ce0O gives rise to a range of important technological applications because of its oxygen storage capacity at moderate temperatures as below: CeO2=CeO2.x+ X/2O2 [2]. The oxygen storage phenomenon gives ceria important technological uses in different fields as automobile exhaust purification catalyst [3-4], fluorescent powder, ultraviolet absorption material [5], polishing powder, fuel cell materials [ 6], and gas sensors, etc. The excellent properties of CeO2 nano powder make its synthesis and preparation become one of the hot spots of world scientists study."

Jan 1, 2013

By L. M. Luckevich

Gypsum is a product from the neutralization of sulfuric acid by lime or limestone. This paper will discuss specifications for gypsum used in wallboard, cement and agriculture and the factors affecting its utilization potential. Process conditions during the neutralization which enhance or inhibit utilization potential will be included. In addition, this paper provides a technical and economic perspective of the gypsum industry in North America with a view to the factors affecting the utilization of synthetic gypsum in traditional applications. Current production and consumption of natural and synthetic gypsum in Nonh America are described and the impact of their differences on utilization options are discussed.

Jan 1, 1996

By Stanislatv Pawlowski

New, large sulphur deposits were discovered in Poland in 1953, the result of investigations by the National Geological Institute. All deposits occur in a widespread Miocene evaporite unit in the Carpathian foredeep. The gypsum underlying impermeable Sarmatian clays was altered to limestone and native sulphur where penetrated by hydrocarbons and bacteria. All deposits occur in Miocene structural uplifts. The early determination of the genesis of the sulphur deposits and their occurrence in elevated blocks led to an exploration program that successfully located new deposits.

Jan 1, 1978

By Donald G. Dahle

Project Payette is a conceptual nuclear experiment under the Vela Uniform program intended to further evaluate the mechanism of seismic decoupling. Vela Uniform is a Department of Defense program to improve this country's capability to detect, locate and identify underground nuclear detonations. This program evolved from recommendations of the Panel on Seismic Improve¬ment, (Berkner Panel), an officially appointed group of noted U. S. scientists. This Panel, taking note of difficulties in detecting the differences between some underground nuclear detonations and some earthquakes recommended a program of increased basic research in seismology. The theory of decoupling, Which involves possible reducing of seismic motion resulting from underground explosions by reducing the coupling or physical linkage between the explosion and the geologic environment, was investigated by Dr. Albert latter and his associates at RAND during the late 1950's. The concept has been further investigated theoretically by scientists of the Lawrence Radiation Laboratory and the Sandia Laboratory. The theory has been tested experimentally under Vela Uniform Projects Cowboy, Dribble and Sterling. The Salmon Event of Project Dribble was a tamped (with the explosive in firm contact with the geologic formation) nuclear detonation 2700 feet below ground in the Tatum Salt Dome. Project Payette, if found to be feasible and if authorized for actual execution, would become a decoupled experiment in the same environment.

Jan 1, 1968

By Longjiang Li, Mao Jiang, Zhihui Shen, Guizhou University, Yin Pan

This paper aims to study the influence and action mechanism of collector Y-89 on the flotation of auriferous pyrite. The measurement to identify adsorption quantity, IR and XPS spectrum analysis and flotation experiment made on the pure mineral were conducted. The research results show that when the dosage of MIBC is 20 mg/L, and pH of 8, the dosage of Y-89 over 60 mg/L, the pyrite recovery rate is greater than 80%.And when the dosage of Y-89is 60 mg/L, dosage of MIBC 20 mg/L, the pH in a wider range (pH=4~9), the recovery is greater than 75%. When the pH is above 10, the pyrite is depressed and its recovery rate is found to be dramatically dropping. Adsorption quantity measurement also shows that the strong alkaline conditions inhibit the adsorption of Y-89 on the surface of auriferous pyrite. IR measurement indicates that chemisorption of Y-89 occurs on the surface of auriferous pyrite. XPS spectrum analysis indicates that without adding Y-89, oxidation reaction occurs on the surface of pyrite. But when Y-89 is added, the chemical environment of Fe on the surface of pyrite has changed. Such findings indicate that with Y-89, chemisorption occurs on the surface of auriferous pyrite.

Jan 1, 2014

By Björn Saxen

Outotec atmospheric Direct Leaching has so far been implemented for zinc production capacities of around 100,000 t/a. Lately, there has been growing interest for small scale direct leaching plants, producing circa 30,000 t/a of Zn. Such small leaching plants can provide extra front-end capacity in existing roaster-based plants and enable treatment of feed materials not suitable for roasting. In small scale plants the proven OKTOP® 9000 Direct Leaching reactors are not readily applicable, due the large size. For smaller installations a modular approach is proposed providing multiple advantages, such as reducing the construction time and amount of the site work required causing less disturbance to regular plant operation with reduced cost. In this paper, we present advantages that can be achieved by using modular OKTOP®C reactors and discuss also process design when connecting a small scale direct leaching process to an existing zinc plant. Also benefits of direct leaching expansion are presented.

By S. J. Swan

A computerized on-line process control system designed to monitor and control the seven-cone copper precipitation operations at Kennecott Copper Corporation's Chino Mines Division in New Mexico has been continuously operating since April, 1972. The cone monitoring system consists of plant sampling components, process measurement instrumentation, on-stream X-ray spectrometer, control computer, typewriters for programming and for operating reports, foreman's communication console, and cone automation hardware. The system provides the following functions: (1) assays for copper and iron from ten process streams on a continuous rotating basis, (2) directs hardware to automatically flush and start up cone units based on measured performance variables, (3) provides continuous plant operating data and calculates metallurgical averages as well as production figures for shift and daily summaries, and (4) provides data logging capabilities. The system is very reliable and improves plant performance by increasing yields, reducing scrap iron consumption, and reducing operating manpower requirements.

Jan 1, 1975

By L. B. Pankratz

Heat contents, measured above 298.15° K, and derived entropy increments are presented in tabular and equation form for the two crystalline forms of zinc sulfide (sphalerite and wurtzite) and for four solid solutions of iron and zinc sulfides having the compositions Zno.,,6Fe0.302S, Zno.750Fe0.250S, Zno.650Fe0.3505, and Zno.498Feo.502S.

Jan 1, 1965

By Norman B. Davis

THE ceramic group of industries is comprised of those engaged in the manufacture of cement, glass, artificial abrasives, whiteware, including earthenware, stoneware, porcelain tableware, porcelain sanitary ware, electrical porcelain, floor and wall tile, porcelain enamel on metals, refractories of all kinds, sewer-pipe and structural clay products, such as terra cotta, brick, and hollow tile. The various sub-divisions of the industry produce a wide range of articles on which we depend for our creature comforts from day to day, perhaps to a greater extent than we generally realize. The industry, in turn, depends on a great number of minerals, and chemical products derived from minerals, and it is the object of this brief paper to present a list of these with notes indicating the particular applications. In order to bring home the importance of the industry to your daily life, stop and consider the many things around you accepted as a matter of course. Cement provides the smooth surfaces of many of our highways, city streets, and sidewalks. It enters into nearly all types of construction, alone or in combination with other clay products. Glass we hardly appreciate because we can see through it so easily, but it is there to serve us in windows, doors, and other light-transmitting structures. Glass is the universal means of transporting liquids and beverages, our beverages are usually served in it, and, with the recent development in fine spun glass textiles, there is a possibility of glass clothing in the future. Chinaware, a general term for table dishes, may be earthenware (not vitrified), semi-porcelain, or bone china, but it is before us three or more times a day ?and we seldom think of the minerals that have made these products possible. Floor tile, wall tile, and other ceramic specialties for interior and exterior use and decoration please the eye and provide sanitary surroundings.

Jan 1, 1938

By Hongfa Hu, Stavros A. Argyropoulos, Stephan Ferenczy

"Physical as well as mathematical modeling was carried out to investigate the exothermic mass transfer in liquid metal systems. In these systems, the exothermicity induces unique heat, mass and momentum transfer phenomena. Moreover, these phenomena are deeply coupled and they are further complicated by the presence of a moving boundary.In the physical model used, ice cylinders were immersed into sulfuric acid solutions, because the intermixing of ice with sulfuric acid is very exothermic. In this low temperature system, velocity and temperature measurements in the sulfuric acid were made as well as measurements of the ice melting in the sulfuric acid.The mathematical model developed solved simultaneously the heat, mass and momentum equations numerically, utilizing the control-volume finite difference approach. The enthalpy method was adopted to track the moving boundary. Predictions made by the mathematical model were in close agreement with the results obtained by the physical model.The results from the mathematical model were further validated with experiments involving high temperature liquid metals. Specifically, data were obtained in an experimental setup involving (a) dipping silicon cylinders into high carbon liquid iron and (b) dipping nickel cylinders into liquid aluminum. Results from these experimental studies supported the predictions of the mathematical model."

Jan 1, 1999

By H. E. Peterson

A study was undertaken by the Bureau of Mines to develop a simple, reliable test for field detection of selenium in rocks and soils. Two methods are described for qualitative detection of selenium, dependent upon its form of occurrence and the presence of interfering constituents in the sample. Both methods involve fusion of the sample in a test tube to form elemental selenium that will volatilize and condense as a red deposit on the cooler upper portion of the test tube. The methods are sensitive to 10 parts per million, (p.p.m.) equivalent to 0.001 percent, and can be made semiquantitative by using suitable standard samples. INTRODUCTION Although selenium is widely distributed in the United States, the known deposits are either so small or so low grade that they cannot be processed economically for selenium alone-4/ At present, commercial production is a byproduct of the smelting and refining of base-metal ores, particularly copper.5/ About 0.75 pound of selenium is recovered per ton of electrolytic copper, and small amounts are recovered by special treatment of assorted smelter dusts and fume products. Since selenium is a strategic metal in short supply, new sources are being sought by both Government and private interests.

Jan 1, 1957

By A. E. Petersen

The United States Bureau of Mines conducted research on high-intensity magnetic separation methods for upgrading tantalum concentrates from Alabama. Process flow sheets were studied to maximize tin removal and minimize tantalum loss. Using laboratory-scale equipment, concentrates were produced which contained over 65% combined Ta2O5-Nb2O5. Up to 78% of the tin was recovered as a byproduct, containing about 70% SnO2. Only 1 to 5% of the tantalum reported with the tin byproduct. The producer subsequently incorporated high-intensity magnetic separation into its process flow sheet to provide concentrates for the National Defense Stockpile.

Jan 1, 1993

By Niloy K. Nath

Two layer sintering by charging green sinter mix with normal coke rate in the upper layer and reduced coke rate in the lower layer, can substantially reduce the coke rate and also improve the sinter quality by producing more uniform thermal profile through out the bed height. The two-layer sintering process have been analyzed by numerical simulation of the process by a detailed CFD based model, considering all the important phenomena like gas-solid reaction, melting and solidification, flow through porous bed, heat and mass transfer etc. Optimization techniques like genetic algorithm, differential evolution is then applied to evaluate the optimum coke rate in the two layers of the bed to produce the ideal thermal profile and melting fraction in the sinter bed for optimum sinter quality. Through this optimization method both high quality sinter with minimum return fines can be achieved along with reduced coke rate. Application of a genetic algorithm for this type of process optimization has several advantages over the traditional optimization techniques since it can identify global optimum condition and perform multi-objective optimization much easily for complex industrial process like iron ore sintering. Keywords: Two-layer Sintering, Iron Ore Sinter Quality, Ergun's Equation, Gas-solid reaction, Melting Fraction, Multi Objective Optimization, Pareto Set, Genetic Algorithm

Jan 1, 2003

By Young Hyun Paik, Hyung Sup Choi, Yeun Sik Kim

The basic studies on the surface properties and flotation characteristics of ilmenite were made by electrophoretic, adsorption, contact-angle and floatability measurements. The isoelectric point of ilmenite is found to be at pH 5.6. By combining the results of electrokinetic studies and adsorption measurements, a clearer picture of the ilmenite-solution interface was observed. These findings were correlated with the floatability of ilmenite obtained by Hallimond tube tests. The general flotation characteristics of ilmenite are compared with those obtained for magnetite and rutile. It is indicated that the above three minerals, namely, ilmenite, magnetite and rutile, have very similar surface properties and flotation characteristics. Therefore, it is difficult to make an effective separation of these minerals by flotation. However, it is found that sodium orthophosphate acts as a selective depressant for magnetite in anionic flotation. Therefore, close pH control of the pulp in the presence of the phosphate ion enhances the possibility for a successful separation of these minerals.

Jan 1, 1967

By R. L. Hopkins

The work described was performed to determine whether sulfur compounds of the thienothiophene class occur in crude oil. The presence or absence of various classes of sulfur compounds in crude oils is of interest and value to petroleum science. The Bureau of Mines, for the first time, identified hydro-carbon products of desulfurization that point directly to the identity of two individual thienothiophenes, namely 3-methylthieno[2,3-b]thiophene and 2-meth-ylthieno[3,2-b]thiophene, in Wasson, Texas, crude oil. These identifications, described in detail, were accomplished using microdesulfurization, mass spectrometry, and gas-liquid chromatography.

Jan 1, 1966

By Nestor Cezar Heck

Aim of the present work is to continue the theoretical evaluation of the slags of the fundamental system CaO-SiO2-CrOx-MgO (Ca-O-Cr-Si-Mg quinary system) at the temperature of 1,873 [K], with the help of a computational thermodynamic tool. Driving force for this and the previous research works is the understanding of chromium losses from the molten bath into the slag. Especially motivating is the presence of solid phases in the slag, since they may prevent refractory degradation and help in the production of foaming slags. Nevertheless, Cr-bearing solid phases can lead to Cr losses, being therefore detrimental. Determination of the states of thermodynamic equilibrium for this system using a slag with fixed composition as a start material were made using MgO amount as variable. Results show the impact of the MgO content on the equilibrium phases (molten metal, liquid slag, solids) and their composition for this system.

Jul 30, 2018

By Steven L. Webb

In 1965, Monsanto started planning of a new dike (No. 15) for use in disposing of ore tailings at its Columbia, Tennessee phosphorus plant. Generally, in the phosphorus industry only clay tailings are produced making it necessary to borrow fill for construction of a retaining dike. Borrow area investigations indicated that weathered shales and limestones adjacent to the dam site would provide adequate construction materials. It was proposed that the more clayey weathered shales would be used for the impervious core and the more granular weathered limestones would be placed in the outer shell of the dike. A dike section is shown in Figure 1 with gradation curves for core and shell materials in Figure 2. Figure 3 shows an aerial view of the tailings pond and dike during first-stage construction. Although the borrow area explorations indicated that the weathering of the sedimen-tary deposits was highly irregular, it was not considered necessary, at the time, to specify special excavation techniques that would ensure a thorough blending of the materials in the borrow pit. Instead, because of the short haul distance, a scraper operation for both clay core and granular shell materials was adopted as the most economical construction method. Using this materials-handling technique, variations in permeability could be expected in the compacted layers inthe embankment. Where continuous layers of less clayey limestones were placed in the core of the dam, extending from the upstream to downstream shells, seepage losses would be expected to increase substantially. Upon completion of the damn 1966, and shortly after reservoir filling, it was apparent that the construction technique used had resulted in the formation of pervious layers through the clay core. Excessive seepage on the downstream face of the dike was noticeable within a very short time. A monitoring program was established, using piezometric observations and flow measurements. These data indicated that seepage should be reduced and the application of an asphaltic emulsion

Jan 1, 1971

By M. G., Corson

1. In addition to the alloys of copper with iron previously found by Hanson and Ford to show an increase in the concentration of the alpha range with increase in temperature the following binary and ternary systems have been found by the author to exhibit: the same feature: (a) Copper-chromium. (b) Copper-cobalt. (c) Copper-silicon. (d) Copper-nickel-silicon and its pseudo-binary section Cu-Ni2Si (formula of compound definitely established). (e) Copper-cobalt-silicon and its pseudo-binary section Cu-Co2Si (formula of compound established with some probability but not as definitely as for Ni2Si). (f) Copper-chromium-silicon; formation of a compound definitely established (compare Figs. 1 and 2). The formula of this compound may be either Cr2Si or Cr3Si. (g) Copper-iron-silicon; presence of a phase containing both iron and silicon established in an indirect way only. No definite microconstituents observed. 2. RANGES OF SOLID SOLUBILITY (percentage at various tempera¬tures). (a) For copper-chromium: 0.8 at 1000° C.; 0.5 at 900° C.; 0.25 at 800° C.; 0.05 to 0.1 at 500° C. (b) For copper-cobalt: 3.4 at 1000'C.; 2.4 at 900'C.; 1.7 at 800'C.; 0.9 at 600°C.; 0.35 at room temperature. (c) For copper-silicon (Fig. 3) : 6.8 ± 0.1. per cent. at 800° C.; 3 per cent. at 400° C. and probably below 2 per cent. at room temperature if sufficiently long annealed. (d) For copper-cobalt silicide: 3.3 at 1000° C.; 2.4 at 900° C.; 1.6 at 800° C.; 0.7 at 600° C.; 0.3 at 300° C. (e) For copper-nickel silicide (Fig. 4): 8.2 at 1000° C.; 5.5 at 900° C.; 3.6 at 800° C.; 1.6 at 600° C.; 0.7 at 300° C.

Jan 1, 1927

By A. D. Zunkel

The zinc in electric arc furnace dust (EAFD) arises from the fuming and oxidation of the zinc present, mainly as galvanizing, in automotive scrap. The dust is collected from the electric furnace offgases in bag filters and is classified by the EPA as a hazardous waste (K061). As more zinc is used in galvanized sheet on automobiles and more automobile scrap is recycled via the EAF, the more zinc will be available for recovery and recycling. EAFD will become a more prevalent and important source of zinc compared to the traditional zinc sulfide concentrates ifit can be cost effectively processed.

Jan 1, 1995